Supplementary Online Content

Supplementary Online Content Valley TS, Sjoding MW, Ryan AM, Iwashyna TJ, Cooke CR. Association of intensive care unit admission with mortality among older patients with pneumonia. JAMA. doi:10.1001/jama.2015.11068. etable 1. International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) codes efigure 1. Study selection criteria/recruitment table eappendix 1. Appendix on statistical methods for the instrumental variable analysis etable 2. Instrument analysis relationship between ICU admission and differential distance (condition #1) etable 3. Patient characteristics by median differential distance etable 4. Instrument analysis absence of relationship between 30-day mortality and differential distance (condition #2) etable 5. Instrument analysis absence of relationship between Medicare spending and differential distance (condition #2) etable 6. Instrument analysis absence of relationship between hospital costs and differential distance (condition #2) etable 7. Hospital characteristics by ICU admission quintiles efigure 2. Conceptual diagram of the marginal population identified by instrumental variable model eappendix 2. Inverse probability weighting etable 8. Elixhauser comorbidities by ICU admission etable 9. Instrumental variable analysis model results for 30-day mortality etable 10. Instrumental variable analysis model results for Medicare spending etable 11. Instrumental variable analysis model results for hospital costs etable 12. Instrumental variable analysis on costs per patient by in-hospital mortality ereferences This supplementary material has been provided by the authors to give readers additional information about their work.

etable 1. International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM) Codes Diagnosis ICD-9-CM Codes Pneumonia 480.0-480.3, 480.8, 480.9, 481, 482.0, 482.1, 482.2, 482.30-482.32, 482.39-482.41, 482.49, 482.81-482.84, 482.89, 482.9, 483.0, 483.1, 483.8, 485, 486, 487.0 Viral pneumonia 480.0-480.3, 480.8, 480.9, 487.0 Bacterial pneumonia 481, 482.0, 482.1, 482.2, 482.30-482.32, 482.39-482.41, 482.49, 482.81-482.84, 482.89, 482.9, 483.0, 483.1, 483.8 Acute respiratory failure 518.81, 518.82, 518.84, 799.1 Sepsis 038.x, 785.52, 995.91, 995.92 Shock 458, 785.5-785.59, 958.4, 998.0 Respiratory or cardiac arrest 427.5, 799.1 Procedures Mechanical ventilation 96.7, 96.70, 96.71, 96.72, 93.90 Cardiopulmonary resuscitation 99.60, 99.63

efigure 1. Study selection criteria/recruitment table 1,327,370 Admissions to patients with eligible ICD-9- CM for pneumonia from 2010 to 2012 105,963 Excluded (8.2%) 47,488 Transferred in from another hospital (3.6%) 40,112 In hospitals without ICU capabilities (3.0%) 18,239 Missing geographic coordinates (1.6%) 124 Admissions to U.S. territories (0.01%) 1,221,407 Admissions met study inclusion criteria 109,013 Excluded as readmissions in the same year (9.0%) 1,112,394 Patients with a single hospitalization per year 328,404 ICU patients 783,990 Ward patients

eappendix 1. Appendix on statistical methods for the instrumental variable analysis The instrument for this study was differential distance, defined as the difference between 1) the distance between a patient s residence to the nearest high ICU use hospital and 2) the distance from a patient s residence to the nearest hospital of any type. For the instrument to be considered valid, it must meet three conditions. Conditions #1 and #2 can be demonstrated empirically. Condition #3 cannot be proven but can be evaluated. 1 Condition 1. The instrument must be associated with the treatment. In this study, differential distance must be associated with ICU admission. As demonstrated in etable 2, differential distance is highly correlated with ICU admission (Partial F (1, 2986) = 245), conditional on other covariates. A general rule of thumb is that an instrument is strong if it has an F-statistic > 10. 2,3 For every 10-mile increase in differential distance, the probability of ICU admission decreases by 1.5. When stratified by the median differential distance (3.3 miles), ICU admission was 36% in the lower half and 23% in the upper half. Condition 2. The instrument must not be associated with the outcome, except through the treatment. In this study, differential distance should not be associated with 30-day mortality, Medicare payments, or hospital costs, except through ICU admission. As demonstrated in etables 4-6, differential distance is not correlated with 30-day mortality (P value = 0.92), Medicare payments (P value = 0.21), or hospital costs (P value = 0.07), conditional on other covariates. Condition 3. There should be no mutual confounders between the instrument and the outcome. This condition cannot be proven. Instead, it can be evaluated by examining covariate balance as stratified by the instrument. In etable 3, patient characteristics are stratified by median differential distance. In etable 7, hospital characteristics are stratified by quintiles of ICU admission rate. Distance instruments are inherently linked to urbanicity (and other associated factors such as race and socioeconomic status). 4 Using differential distance instead of absolute distance attenuates this association but rarely prevents it. Although it is not clear if adjustment for or stratification by covariates with imbalance in the IV model eliminates bias, this is the recommended approach to covariates with any imbalance. 4 All models were adjusted for patient characteristics listed in Table 1 and hospital characteristics listed in Table 2. All 29 Elixhauser comorbidities were included in models individually. Angus organ failure score, 5 which identifies severity of illness by patient organ failures derived from the administrative record with a maximum score of six and higher scores indicating more organ failures, included all organ failures numbered 0 to > 5. Hospital region comprised the nine regions by U.S. census definitions. All models adjusted standard errors for clustering of patients within hospitals. Test of endogeneity To determine if the IV model estimating the relationship between ICU admission and the outcomes improves upon a standard model fit without the IV, the Durbin-Wu-Hausman test of endogeneity was performed for each outcome. Results for 30-day mortality (F statistic = 16.1, p<0.001), Medicare spending (F statistic = 14.2, p<0.001), and hospital costs (F statistic = 7.9, p<0.01) were each significant, indicating that the ordinary least-squares model results in biased estimations when compared to the instrumental variable analysis. 2

etable 2. Instrument analysis relationship between ICU admission and differential distance (condition #1) F-statistic (1, 2986) P value Adj. R- squared Beta 95% CI -0.015 absolute change in ICU admission probability for every 10 mile increase in differential distance (-0.02, -0.01) 245 < 0.001 0.47 Condition #1 Beta 95% Conf. Interval P value Differential distance per 10 miles -0.015-0.02, -0.01 < 0.001 Age 75-84 years -0.022-0.024, -0.021 < 0.001 > 85 years -0.057-0.06, -0.055 < 0.001 Sex -0.007-0.009, -0.006 < 0.001 Race Black -0.006-0.011, -0.001 0.03 Other 0.012 0.005, 0.019 0.001 Admission Source Emergency department -0.001-0.005, 0.003 0.55 Urbanicity Large Suburban Metropolitan -0.001-0.011, 0.01 0.89 Medium Metropolitan -0.0004-0.013, 0.012 0.95 Small Metropolitan 0.007-0.008, 0.021 0.38 Micropolitan 0.027 0.014, 0.04 < 0.001 Noncore 0.023 0.011, 0.036 < 0.001 Median Income by Categories Median Income $40,000-$100,000-0.006-0.01, -0.001 0.02 Median Income > $100,000-0.004-0.013, 0.005 0.36 Angus Organ Failure Score 1 0.130 0.127, 0.133 < 0.001 2 0.218 0.212, 0.223 < 0.001 3 0.106 0.097, 0.115 < 0.001 4 0.082 0.071, 0.093 < 0.001 > 5 0.079 0.064, 0.093 < 0.001 Elixhauser Comorbidities Congestive Heart Failure 0.058 0.056, 0.061 < 0.001 Valvular Disease 0.013 0.009, 0.018 < 0.001 Pulmonary Circulation Disorders 0.028 0.024, 0.033 < 0.001 Peripheral Vascular Disorders 0.009 0.006, 0.013 < 0.001 Hypertension -0.029-0.031, -0.027 < 0.001 Paralysis 0.020 0.015, 0.024 < 0.001 Other Neurological Disorders -0.008-0.011, -0.005 < 0.001 Chronic Pulmonary Disease -0.009-0.011, -0.007 < 0.001 Uncomplicated Diabetes -0.011-0.013, -0.009 < 0.001 Complicated Diabetes -0.011-0.015, -0.006 < 0.001 Hypothyroidism -0.018-0.02, -0.015 < 0.001 Renal Failure -0.003-0.005, -0.001 0.01 Liver Disease -0.005-0.012, 0.002 0.20 Peptic Ulcer Disease 0.052-0.005, 0.109 0.07 AIDS -0.009-0.039, 0.02 0.55 Lymphoma 0.013 0.006, 0.02 < 0.001 Metastatic Cancer 0.004 0.0003, 0.008 0.03 Solid Tumor 0.005 0.001, 0.008 0.01 Collagen Vascular Disease -0.010-0.014, -0.006 < 0.001 Coagulopathy -0.039-0.043, -0.034 < 0.001 Obesity -0.010-0.014, -0.006 < 0.001 Weight Loss 0.034 0.03, 0.038 < 0.001 Fluid and Electrolyte Disorders 0.016 0.015, 0.018 < 0.001 Blood Loss Anemia 0.020 0.009, 0.031 < 0.001 Deficiency Anemias -0.021-0.023, -0.019 < 0.001 Alcohol Abuse 0.033 0.019, 0.046 < 0.001 Drug Abuse 0.013-0.01, 0.036 0.28 Psychoses -0.004-0.009, 0.001 0.16 Depression -0.026-0.029, -0.023 < 0.001 Mechanical ventilation 0.336 0.327, 0.345 < 0.001 Cardiopulmonary resuscitation 0.004-0.004, 0.012 0.30 Respiratory failure 0.206 0.2, 0.213 < 0.001

Sepsis 0.114 0.109, 0.12 < 0.001 Shock 0.193 0.186, 0.2 < 0.001 Arrest 0.049 0.042, 0.056 < 0.001 Type of Pneumonia Viral Pneumonia 0.005-0.002, 0.013 0.19 Bacterial Pneumonia 0.012 0.008, 0.016 < 0.001 Region Mid-Atlantic -0.009-0.03, 0.013 0.42 South Atlantic 0.017-0.005, 0.038 0.13 East North Central 0.018-0.003, 0.039 0.10 East South Central 0.031 0.007, 0.054 0.01 West North Central 0.026 0.002, 0.049 0.03 West South Central 0.041 0.018, 0.064 < 0.001 Mountain 0.015-0.008, 0.039 0.20 Pacific 0.007-0.018, 0.032 0.60 Hospital Ownership Type For-profit 0.016 0.005, 0.028 0.01 Government 0.003-0.008, 0.015 0.55 Hospital Teaching Status (Ratio of Resident FTE to Hospital Beds) -0.058-0.081, -0.036 < 0.001 Hospital Size by Beds, per 100 Beds 0.004 0.001, 0.01 0.01 ICU Size by Proportion of Hospital Beds 5-10% -0.003-0.015, 0.009 0.62 > 10% 0.021 0.007, 0.034 0.003 Proportion of Medicaid Patients Served, per Hospital Admission -0.018-0.103, 0.066 0.67 Hospital Technology Index a < 0.001-0.001, 0.0001 0.17 Hospital Nursing Ratio, Nurse FTE per 1,000 Patient-Days -0.001-0.004, 0.002 0.55 Hospital Annual Pneumonia Case Volume, per 100 Cases -0.02-0.03, -0.02 < 0.001 Year of Admission 2011-0.007-0.009, -0.004 < 0.001 2012-0.013-0.017, -0.01 < 0.001 Constant 0.160 0.134, 0.185 < 0.001 a The technology index is a weighted sum of the following hospital capabilities: obstetrics, medical/surgical intensive care unit, cardiac intensive care unit, emergency department, trauma center, open heart surgery, radiation therapy, computed tomography, diagnostic radiology, magnetic resonance imaging, positron-emission tomography, single-photon emission computed tomography, ultrasonography, and transplantation service. The beta for technology index represents change in one unit of the technology index per one unit change of the outcome.

etable 3. Patient characteristics by median differential distance Characteristics < 3.3 miles No. (%) > 3.3 miles No. (%) No. Patients a 553,597 558,797 ICU Admission 201,144 (36.3) 127,260 (22.8) Age, mean (SD) 80 (8) 80 (8) 65-74 years 172,791 (31.2) 170,502 (30.5) 75-84 years 195,113 (35.2) 202,474 (36.2) > 85 years 185,693 (33.5) 185,821 (33.3) Female 303,602 (54.8) 302,561 (54.2) Race/Ethnicity White 450,202 (81.3) 511,949 (91.6) Black 65,976 (11.9) 30,671 (5.5) Other 37,419 (6.8) 16,177 (2.9) Urbanicity Large Central Metropolitan 191,181 (34.6) 36,797 (6.6) Large Suburban Metropolitan 139,724 (25.3) 119,372 (21.4) Medium Metropolitan 113,734 (20.6) 126,148 (22.6) Small Metropolitan 42,604 (7.7) 92,341 (16.6) Micropolitan 36,842 (6.7) 108,219 (19.4) Noncore 28,503 (5.2) 74,499 (13.4) Median Household Income by Zip Code < $40,000 138,696 (25.1) 155,669 (27.9) $40,000-$100,000 378,111 (68.3) 375,613 (67.2) > $100,000 36,790 (6.7) 27,515 (4.9) Elixhauser Comorbidities Count, mean (SD) 2.6 (1.1) 2.7 (1.1) Congestive Heart Failure 158,167 (28.6) 162,766 (29.1) Valvular Disease 23,850 (4.3) 27,749 (5.0) Pulmonary Circulation Disorders 25,656 (4.6) 26,628 (4.8) Peripheral Vascular Disorders 24,270 (4.4) 26,322 (4.7) Hypertension 276,201 (49.9) 290,923 (52.1) Paralysis 17,309 (3.1) 13,854 (2.5) Other Neurological Disorders 32,813 (5.9) 35,068 (6.3) Chronic Pulmonary Disease 207,142 (37.4) 230,502 (41.3) Uncomplicated Diabetes 102,038 (18.4) 108,859 (19.5) Complicated Diabetes 13,060 (2.4) 13,375 (2.4) Hypothyroidism 56,703 (10.2) 64,546(11.6) Renal Failure 88,570 (16.0) 89,731 (16.1) Liver Disease 4,966 (0.9) 4,375 (0.8) Peptic Ulcer Disease 94 (0.02) 87 (0.02) AIDS 413 (0.1) 136 (0.02) Lymphoma 11,249 (2.0) 11,002 (2.0) Metastatic Cancer 20,997 (3.8) 19,295 (3.5) Solid Tumor 22,938 (4.1) 22,808 (4.1) Collagen Vascular Disease 14,322 (2.6) 16,744 (3.0) Coagulopathy 26,581 (4.8) 23,411 (4.2) Obesity 15,935 (2.9) 17,498 (3.1) Weight Loss 56,937 (10.3) 48,985 (8.8) Fluid and Electrolyte Disorders 208,112 (37.6) 199,601 (35.7) Blood Loss Anemia 2,062 (0.4) 2,578 (0.5) Deficiency Anemias 84,063 (15.2) 89,448 (16.0) Alcohol Abuse 1,231 (0.2) 1,375 (0.3) Drug Abuse 442 (0.1) 425 (0.1) Psychoses 11,448 (2.1) 11,446 (2.1) Depression 29,479 (5.3) 36,332 (6.5)

Admission Source Outpatient 429,586 (77.6) 439,961 (78.7) Emergency Department 121,857 (22.0) 117,037 (20.9) Hospital Diagnoses Pneumonia as Primary Diagnosis 353,378 (63.8) 401,174 (71.8) Respiratory Failure 190,355 (34.4) 157,614 (28.2) Sepsis 137,583 (24.9) 108,498 (19.4) Shock 63,005 (11.4) 36,712 (6.6) Cardiac or Respiratory Arrest 6,659 (1.2) 4,663 (0.8) Type of Pneumonia Unspecified Pneumonia 479,638 (86.6) 483,295 (86.5) Viral Pneumonia 5,778 (1.0) 5,474 (1.0) Bacterial Pneumonia 68,181 (12.3) 70,028 (12.5) Procedures Performed during Hospitalization Mechanical Ventilation 109,635 (19.8) 72,236 (12.9) Cardiopulmonary Resuscitation 6,975 (1.3) 4,097 (0.7) Angus Organ Failure Score b 0 329,346 (59.5) 376,960 (67.5) 1 136,563 (24.7) 125,685 (22.5) > 2 87,688 (15.8) 56,152 (10.1) Year of Admission 2010 178,628 (48.5) 189,737 (51.5) 2011 194,431 (50.7) 189,082 (49.3) 2012 180,538 (50.1) 179,978 (49.9) Outcomes < 3.3 miles No. (%) > 3.3 miles No. (%) No. Patients 553,597 558,797 Length of Stay in Days, median (IQR) c 5 (3-8) 4 (3-7) Quartiles of Total Medicare Payment per Patient 1 ($0-$4,981) 118,840 (21.5) 159,453 (28.5) 2 ($4,982-$7,639) 128,207 (23.2) 149,776 (26.8) 3 ($7,640-$11,162) 137,196 (24.8) 140,879 (25.2) 4 ($11,163-$882,637) 169,354 (30.6) 108,689 (19.5) Quartiles of Hospital Costs per Patient 1 ($153-$4,614) 124,569 (22.6) 152,278 (27.3) 2 ($4,615-$7,389) 127,354 (23.1) 149,540 (26.9) 3 ($7,390-$13,154) 136,440 (24.8) 140,445 (25.2) 4 ($13,155-$1,375,266) 162,127 (29.5) 114,764 (20.6) Discharge Destination Home 271,652 (49.2) 299,801 (54.2) Rehabilitation or Nursing Facility 173,853 (31.5) 166,097 (30.0) Dead 64,508 (11.7) 50,583 (9.1) Other 41,997 (7.6) 36,909 (6.7) 30-Day Readmission 97,188 (17.6) 96,774 (17.3) 30-Day Mortality 113,578 (20.5) 96,482 (17.3) a 11,703 (1%) of patients were excluded from regression models due to missing differential distance (n=5,166), admission source (n=4,053), urban/rural (n=2,430), pneumonia volume (n=107) b Measures severity of illness by patient organ failures from the billing record with a high score of six and higher scores indicating more failures c Interquartile range

etable 4. Instrument analysis absence of relationship between 30-day mortality and differential distance (condition #2) Beta 95% CI F-statistic (1, 2986) P value 0.00004 absolute increase in 30-day mortality for every 10 mile increase in differential distance (-0.0006, 0.0007) 0.01 0.92 Condition #2 Beta 95% Conf. Interval P value Differential distance per 10 miles 0.00004-0.0006, 0.0007 0.92 Age 75-84 years 0.050 0.048, 0.052 < 0.001 > 85 years 0.123 0.12, 0.126 < 0.001 Sex -0.007-0.008, -0.005 < 0.001 Race Black -0.021-0.024, -0.018 < 0.001 Other -0.018-0.022, -0.014 < 0.001 Admission Source Emergency department 0.042 0.039, 0.045 < 0.001 Urbanicity Large Suburban Metropolitan 0.005 0.001, 0.009 0.01 Medium Metropolitan 0.006 0.001, 0.01 0.01 Small Metropolitan 0.006 0.001, 0.011 0.02 Micropolitan 0.013 0.008, 0.017 < 0.001 Noncore 0.014 0.009, 0.019 < 0.001 Median Income by Categories Median Income $40,000-$100,000-0.002-0.005, -0.0002 0.04 Median Income > $100,000-0.002-0.006, 0.002 0.34 Angus Organ Failure Score 1 0.058 0.051, 0.065 < 0.001 2 0.109 0.098, 0.121 < 0.001 3 0.130 0.121, 0.139 < 0.001 4 0.220 0.206, 0.233 < 0.001 > 5 0.312 0.284, 0.34 < 0.001 Elixhauser Comorbidities Congestive Heart Failure 0.011 0.008, 0.015 < 0.001 Valvular Disease -0.016-0.019, -0.013 < 0.001 Pulmonary Circulation Disorders 0.007 0.004, 0.011 < 0.001 Peripheral Vascular Disorders 0.007 0.004, 0.01 < 0.001 Hypertension -0.040-0.042, -0.037 < 0.001 Paralysis 0.021 0.016, 0.026 < 0.001 Other Neurological Disorders 0.013 0.01, 0.015 < 0.001 Chronic Pulmonary Disease -0.043-0.045, -0.041 < 0.001 Uncomplicated Diabetes -0.017-0.019, -0.015 < 0.001 Complicated Diabetes -0.034-0.038, -0.031 < 0.001 Hypothyroidism -0.022-0.024, -0.02 < 0.001 Renal Failure 0.021 0.019, 0.023 < 0.001 Liver Disease 0.046 0.039, 0.053 < 0.001 Peptic Ulcer Disease 0.004-0.048, 0.056 0.88 AIDS 0.022-0.008, 0.052 0.15 Lymphoma 0.050 0.045, 0.056 < 0.001 Metastatic Cancer 0.279 0.274, 0.285 < 0.001 Solid Tumor 0.136 0.131, 0.14 < 0.001 Collagen Vascular Disease -0.012-0.015, -0.009 < 0.001 Coagulopathy -0.021-0.026, -0.017 < 0.001 Obesity -0.037-0.04, -0.034 < 0.001 Weight Loss 0.073 0.069, 0.077 < 0.001 Fluid and Electrolyte Disorders 0.024 0.022, 0.026 < 0.001 Blood Loss Anemia -0.023-0.033, -0.013 < 0.001 Deficiency Anemias -0.026-0.028, -0.024 < 0.001 Alcohol Abuse -0.016-0.028, -0.004 0.01 Drug Abuse -0.045-0.064, -0.026 < 0.001 Psychoses -0.017-0.021, -0.013 < 0.001 Depression -0.013-0.015, -0.01 < 0.001 Mechanical ventilation 0.110 0.093, 0.127 < 0.001 Cardiopulmonary resuscitation 0.355 0.346, 0.365 < 0.001 Respiratory failure 0.140 0.129, 0.15 < 0.001

Sepsis 0.081 0.074, 0.087 < 0.001 Shock 0.086 0.076, 0.097 < 0.001 Arrest 0.163 0.151, 0.175 < 0.001 Type of Pneumonia Viral Pneumonia -0.052-0.058, -0.046 < 0.001 Bacterial Pneumonia -0.053-0.056, -0.05 < 0.001 Region Mid-Atlantic 0.009 0.002, 0.015 0.01 South Atlantic 0.016 0.01, 0.022 < 0.001 East North Central 0.010 0.004, 0.016 0.001 East South Central 0.026 0.019, 0.033 < 0.001 West North Central -0.0001-0.008, 0.007 0.98 West South Central 0.020 0.013, 0.027 < 0.001 Mountain 0.003-0.007, 0.013 0.54 Pacific -0.001-0.008, 0.007 0.86 Hospital Ownership Type For-profit 0.004 0.0003, 0.008 0.04 Government 0.004-0.00001, 0.008 0.05 Hospital Teaching Status (Ratio of Resident FTE to Hospital Beds) -0.011-0.02, -0.002 0.02 Hospital Size by Beds, per 100 Beds 0.002 0.00007, 0.003 0.04 ICU Size by Proportion of Hospital Beds 5-10% 0.005 0.001, 0.01 0.03 > 10% 0.007 0.002, 0.012 0.01 Proportion of Medicaid Patients Served, per Hospital Admission 0.027-0.005, 0.058 0.10 Hospital Technology Index a -0.0002-0.0004, -0.00006 0.01 Hospital Nursing Ratio, Nurse FTE per 1,000 Patient-Days -0.003-0.005, -0.002 < 0.001 Hospital Annual Pneumonia Case Volume, per 100 Cases -0.007-0.009, -0.005 < 0.001 Year of Admission 2011 0.008 0.005, 0.01 < 0.001 2012 0.003 0.001, 0.006 0.004 Constant 0.042 0.031, 0.052 < 0.001 a The technology index is a weighted sum of the following hospital capabilities: obstetrics, medical/surgical intensive care unit, cardiac intensive care unit, emergency department, trauma center, open heart surgery, radiation therapy, computed tomography, diagnostic radiology, magnetic resonance imaging, positron-emission tomography, single-photon emission computed tomography, ultrasonography, and transplantation service. The beta for technology index represents change in one unit of the technology index per one unit change of the outcome.

etable 5. Instrument analysis absence of relationship between Medicare spending and differential distance (condition #2) Beta 95% CI F-statistic (1, 2986) P value $19.6 per 10 mile increase in differential distance (-11, 25) 1.5 0.21 Condition #2 Beta 95% Conf. Interval P value Differential distance per 10 miles 19.6-11, 25 0.21 Age 75-84 years -467-530.3, -403.6 < 0.001 > 85 years -1185-1267.7, -1102.4 < 0.001 Sex 232 187.1, 276.9 < 0.001 Race Black 1363 1127.8, 1598.1 < 0.001 Other 1439 1208, 1669.8 < 0.001 Admission Source Emergency department -72-188.5, 44 0.22 Urbanicity Large Suburban Metropolitan -1098-1385.2, -810.1 < 0.001 Medium Metropolitan -1913-2224.8, -1601.5 < 0.001 Small Metropolitan -1649-1957.4, -1340.9 < 0.001 Micropolitan -1690-1979, -1401.6 < 0.001 Noncore -1519-1805.9, -1231.5 < 0.001 Median Income by Categories Median Income $40,000-$100,000-107 -229.6, 15.3 0.09 Median Income > $100,000 330 128.4, 532.1 0.001 Angus Organ Failure Score 1 2179 2104.8, 2254.1 < 0.001 2 6679 6437.8, 6921.2 < 0.001 3 12019 11515.4, 12522.2 < 0.001 4 14575 13691.5, 15459.4 < 0.001 > 5 13941 11930.4, 15950.8 < 0.001 Elixhauser Comorbidities Congestive Heart Failure 350 288.3, 412.4 < 0.001 Valvular Disease -529-601.8, -455.4 < 0.001 Pulmonary Circulation Disorders 633 503.8, 763.1 < 0.001 Peripheral Vascular Disorders 420 327.8, 511.3 < 0.001 Hypertension -1105-1168.3, -1042.4 < 0.001 Paralysis 927 751, 1102.2 < 0.001 Other Neurological Disorders -743-804.3, -680.9 < 0.001 Chronic Pulmonary Disease -1086-1147.6, -1023.8 < 0.001 Uncomplicated Diabetes -755-803.7, -707 < 0.001 Complicated Diabetes -628-739.2, -516.8 < 0.001 Hypothyroidism -492-530.4, -453 < 0.001 Renal Failure 609 537.8, 679.9 < 0.001 Liver Disease -283-507.6, -57.6 0.01 Peptic Ulcer Disease 1594-838.7, 4027.2 0.20 AIDS 2955 1413.4, 4495.8 < 0.001 Lymphoma 29-171.7, 229.6 0.78 Metastatic Cancer -239-369.7, -108.3 < 0.001 Solid Tumor 21-93.4, 135.8 0.72 Collagen Vascular Disease -598-673.3, -522.3 < 0.001 Coagulopathy -1677-1866.3, -1487.4 < 0.001 Obesity -695-791.6, -597.9 < 0.001 Weight Loss 2620 2372.6, 2867.8 < 0.001 Fluid and Electrolyte Disorders -268-335.1, -201.9 < 0.001 Blood Loss Anemia 368 164, 572.8 < 0.001 Deficiency Anemias -563-611.4, -515.5 < 0.001 Alcohol Abuse -408-776.6, -38.8 0.03 Drug Abuse -1101-1642.1, -560.4 < 0.001 Psychoses -321-444.3, -197.1 < 0.001 Depression -574-621.8, -527.1 < 0.001 Mechanical ventilation 7572 7298.6, 7845.3 < 0.001 Cardiopulmonary resuscitation -3952-4459.4, -3444.4 < 0.001 Respiratory failure 2931 2815.5, 3046.1 < 0.001 Sepsis 3340 3245.4, 3434 < 0.001

Shock -521-774.3, -267.7 < 0.001 Arrest 2285 1760.6, 2808.5 < 0.001 Type of Pneumonia Viral Pneumonia 259 22.7, 494.6 0.03 Bacterial Pneumonia 3289 3101.1, 3476.6 < 0.001 Region Mid-Atlantic 462 27.6, 896.9 0.04 South Atlantic -1438-1787.9, -1088.9 < 0.001 East North Central -1351-1657.7, -1045.1 < 0.001 East South Central -1899-2241.1, -1556.3 < 0.001 West North Central -1151-1511.5, -790.9 < 0.001 West South Central -2031-2384.3, -1677.7 < 0.001 Mountain -1078-1523.8, -631.5 < 0.001 Pacific 1524 983.6, 2065.2 < 0.001 Hospital Ownership Type For-profit -85-310.6, 140 0.46 Government 415 129, 701.1 0.004 Hospital Teaching Status (Ratio of Resident FTE to Hospital Beds) 3610 2714.6, 4506.3 < 0.001 Hospital Size by Beds, per 100 Beds 58-30, 150 0.21 ICU Size by Proportion of Hospital Beds 5-10% -234-554.3, 85.5 0.15 > 10% -339-639.6, -39.1 0.03 Proportion of Medicaid Patients Served, per Hospital Admission 22178 18981, 25374.7 < 0.001 Hospital Technology Index a -3-12.7, 7.3 0.60 Hospital Nursing Ratio, Nurse FTE per 1,000 Patient-Days -55-125.9, 15.2 0.12 Hospital Annual Pneumonia Case Volume, per 100 Cases 20-120, 160 0.78 Year of Admission 2011 31-51.7, 113.7 0.46 2012-25 -117.1, 67.9 0.60 Constant 7295 6703.1, 7887.4 < 0.001 a The technology index is a weighted sum of the following hospital capabilities: obstetrics, medical/surgical intensive care unit, cardiac intensive care unit, emergency department, trauma center, open heart surgery, radiation therapy, computed tomography, diagnostic radiology, magnetic resonance imaging, positron-emission tomography, single-photon emission computed tomography, ultrasonography, and transplantation service. The beta for technology index represents change in one unit of the technology index per one unit change of the outcome.

etable 6. Instrument analysis absence of relationship between hospital costs and differential distance (condition #2) Beta 95% CI F-statistic (1, 2940) P value -$42 per 10 mile increase in differential distance (-87, 3) 3.3 0.07 Condition #2 Beta 95% Conf. Interval P value Differential distance per 10 miles -42-87, 3 0.07 Age 75-84 years -1101-1187.2, -1015.5 < 0.001 > 85 years -2606-2724.2, -2487.4 < 0.001 Sex 290 233.1, 346.2 < 0.001 Race Black 814 489.7, 1137.7 < 0.001 Other 988 680.1, 1295.8 < 0.001 Admission Source Emergency department -381-522.3, -240.1 < 0.001 Urbanicity Large Suburban Metropolitan -603-1018, -188.3 0.004 Medium Metropolitan -1163-1646.2, -679.5 < 0.001 Small Metropolitan -1130-1600.5, -660.3 < 0.001 Micropolitan -1033-1448.4, -617.2 < 0.001 Noncore -830-1251.4, -408.9 < 0.001 Median Income by Categories Median Income $40,000-$100,000 371 207.5, 534.6 < 0.001 Median Income > $100,000 1174 849.1, 1498.1 < 0.001 Angus Organ Failure Score 1 2581 2497.4, 2664.7 < 0.001 2 7485 7227.5, 7743.5 < 0.001 3 12606 12056.7, 13155.9 < 0.001 4 15517 14487.4, 16546.4 < 0.001 > 5 13837 11510.8, 16163.1 < 0.001 Elixhauser Comorbidities Congestive Heart Failure 1088 999.6, 1176.4 < 0.001 Valvular Disease -693-788.4, -598.3 < 0.001 Pulmonary Circulation Disorders 1267 1103.2, 1431.7 < 0.001 Peripheral Vascular Disorders 303 186.3, 420.7 < 0.001 Hypertension -1790-1866.9, -1712.5 < 0.001 Paralysis 952 726.6, 1177.3 < 0.001 Other Neurological Disorders -1045-1126.6, -963.4 < 0.001 Chronic Pulmonary Disease -1220-1294.7, -1144.4 < 0.001 Uncomplicated Diabetes -1241-1303.4, -1177.8 < 0.001 Complicated Diabetes -1016-1163.6, -869.4 < 0.001 Hypothyroidism -885-939.2, -831.2 < 0.001 Renal Failure 763 658, 868.1 < 0.001 Liver Disease -373-678.1, -68.7 0.02 Peptic Ulcer Disease 4459 1380.6, 7536.7 0.01 AIDS 747-780, 2274.1 0.337 Lymphoma 805 495, 1115.1 < 0.001 Metastatic Cancer -576-741.1, -410 < 0.001 Solid Tumor -101-244.4, 43 0.17 Collagen Vascular Disease -926-1026.4, -824.9 < 0.001 Coagulopathy -1099-1325.6, -872 < 0.001 Obesity -753-871.2, -635.2 < 0.001 Weight Loss 3973 3611.1, 4334.2 < 0.001 Fluid and Electrolyte Disorders -116-198, -34.8 0.01 Blood Loss Anemia 1213 939.1, 1487.4 < 0.001 Deficiency Anemias -681-745.5, -616.3 < 0.001 Alcohol Abuse -102-546.1, 343 0.65 Drug Abuse -1013-1836.5, -189.5 0.02 Psychoses -486-638.3, -333.6 < 0.001 Depression -878-945.5, -809.6 < 0.001 Mechanical ventilation 8843 8559.5, 9126.6 < 0.001 Cardiopulmonary resuscitation -7116-7717.3, -6514 < 0.001 Respiratory failure 3638 3476.7, 3800.1 < 0.001 Sepsis 557 441.3, 673 < 0.001

Shock 2314 1971.6, 2656.6 < 0.001 Arrest 863 168.4, 1557.9 0.02 Type of Pneumonia Viral Pneumonia 1397 1099.6, 1695.2 < 0.001 Bacterial Pneumonia 4247 3978.9, 4515.7 < 0.001 Region Mid-Atlantic 489-280.1, 1257.1 0.21 South Atlantic -1297-1953.4, -640.9 < 0.001 East North Central -906-1551.4, -260.1 0.01 East South Central -1675-2372.9, -976.7 < 0.001 West North Central -568-1305.1, 169.2 0.13 West South Central -1362-2073.8, -649.4 < 0.001 Mountain -548-1366.1, 270 0.19 Pacific 3261 2276.4, 4245.3 < 0.001 Hospital Ownership Type For-profit 368 1.4, 733.8 0.05 Government 344-59, 746.4 0.09 Hospital Teaching Status (Ratio of Resident FTE to Hospital Beds) 1095-226.1, 2417 0.10 Hospital Size by Beds, per 100 Beds 131-19.9, 283 0.09 ICU Size by Proportion of Hospital Beds 5-10% -100-500.5, 301.2 0.63 > 10% -202-615.6, 210.7 0.34 Proportion of Medicaid Patients Served, per Hospital Admission 8714 3676.3, 13751 0.001 Hospital Technology Index a 4-10.1, 18.4 0.57 Hospital Nursing Ratio, Nurse FTE per 1,000 Patient-Days 357 246.5, 468.1 < 0.001 Hospital Annual Pneumonia Case Volume, per 100 Cases -132-331, 66.3 0.19 Year of Admission 2011-48 -156.8, 59.9 0.38 2012-65 -188, 58.9 0.31 Constant 7705 6804.7, 8605.8 < 0.001 a The technology index is a weighted sum of the following hospital capabilities: obstetrics, medical/surgical intensive care unit, cardiac intensive care unit, emergency department, trauma center, open heart surgery, radiation therapy, computed tomography, diagnostic radiology, magnetic resonance imaging, positron-emission tomography, single-photon emission computed tomography, ultrasonography, and transplantation service. The beta for technology index represents change in one unit of the technology index per one unit change of the outcome.

etable 7. Hospital characteristics by ICU admission quintiles Quintile 1 (<19%) No. (%) Quintile 2 (19-25%) No. (%) Quintile 3 (26-32%) No. (%) Quintile 4 (33-44%) No. (%) Quintile 5 (>44%) No. (%) Characteristics No. Hospitals 591 609 595 600 593 Hospital Ownership For-profit 85 (14.4) 107 (17.6) 126 (21.2) 160 (26.7) 201 (33.9) Not-for-profit 413 (69.9) 419 (68.8) 377 (63.4) 345 (57.5) 316 (53.3) Government 93 (15.7) 83 (13.6) 92 (15.5) 95 (15.8) 76 (12.8) Medical School Affiliation 176 (29.8) 175 (28.7) 194 (32.6) 235 (39.2) 218 (36.8) Teaching Status No Residents 483 (81.7) 486 (79.8) 479 (80.5) 447 (74.5) 444 (74.9) Minor Teaching Program (< 0.25 residents/bed) 86 (14.6) 87 (14.3) 84 (14.1) 102 (17.0) 100 (16.9) Major Teaching Program (> 0.25 residents/bed) 22 (3.7) 36 (5.9) 32 (5.4) 51 (8.5) 49 (8.3) Hospital Beds < 100 252 (42.6) 169 (27.8) 147 (24.7) 120 (20.0) 80 (13.5) 100-199 162 (27.4) 184 (30.2) 181 (30.4) 183 (30.5) 190 (32.0) > 200 177 (29.9) 256 (42.0) 267 (44.9) 297 (49.5) 323 (54.5) Percent of ICU Beds < 5% 93 (15.7) 67 (11.0) 79 (13.3) 69 (11.5) 97 (16.4) 5-10% 298 (50.4) 318 (52.2) 266 (44.7) 245 (40.8) 216 (36.4) > 10% 200 (33.8) 224 (36.8) 250 (42.0) 286 (47.7) 280 (47.2) Hospital Pneumonia Annual Case Volume, Mean (SD) 406 (363) 496 (352) 434 (321) 410 (320) 308 (240) Nursing FTE a per 1000 Patient-Days, Mean (SD) 3.7 (1.7) 3.8 (1.4) 3.8 (1.3) 4.0 (1.6) 4.0 (1.4) Technology Index b, Mean (SD) 19.6 (11.9) 21.9 (12.3) 21.2 (12.9) 22.9 (14.6) 20.9 (14.4) Medicaid Patients < 7% 293 (49.6) 234 (38.4) 207 (34.8) 170 (28.3) 100 (16.9) 7-11% 215 (36.4) 219 (36.0) 234 (39.3) 202 (33.7) 204 (34.4) > 11% 83 (14.0) 156 (25.6) 154 (25.9) 228 (38.0) 289 (48.7) Census Regions Northeast 127 (21.5) 127 (20.9) 92 (5.5) 80 (13.3) 68 (11.5) Midwest 188 (31.8) 200 (32.8) 208 (35.0) 226 (37.7) 212 (35.8) South 188 (31.8) 187 (30.7) 194 (32.6) 168 (28.0) 151 (25.5) West 88 (14.9) 95 (15.6) 101 (17.0) 126 (21.0) 162 (27.3) a Full-time equivalents b The technology index is a weighted sum of the following hospital capabilities: obstetrics, medical/surgical intensive care unit, cardiac intensive care unit, emergency department, trauma center, open heart surgery, radiation therapy, computed tomography, diagnostic radiology, magnetic resonance imaging, positron-emission tomography, single-photon emission computed tomography, ultrasonography, and transplantation service.

efigure 2. Conceptual diagram of the marginal population identified by instrumental variable model Example #1: Low-ICU use hospital (a) Never admitted to ICU (b1) Not admitted to ICU (marginal untreated) (c) Always admitted to ICU ICU Admission Threshold Example #2: High-ICU use hospital (a) Never admitted to ICU (b2) Admitted to ICU (marginal treated) (c) Always admitted to ICU ICU Admission Threshold In example #1, the hospital uses the ICU less and has a higher threshold for ICU admission while in example #2, the hospital uses the ICU more frequently and has a lower threshold for ICU admission. In both hospitals, there will be a population of patients who would never be admitted to the ICU (group a ) as well as patients who would always be admitted to the ICU (group c ). At the same time, there will be a group of patients who would either not be admitted (group b1 ) or would be admitted (group b2 ) to the ICU solely because of the hospital to which they presented. These b groups together are the marginal population. In the instrumental variable analysis, differential distance attempts to replicate random assignment of patients as patients living closer to a high-icu use hospital would be more likely to be admitted to this hospital, which would increase their probability of being admitted to the ICU.

eappendix 2. Inverse probability weighting To assess the robustness of the results to the choice of modeling method, the average treatment effect of ICU admission on 30-day mortality was determined using inverse probability weighting (IPW). Inverse probability weighting IPW is a technique that attempts to estimate what one cannot observe - the effect of ICU admission compared to withholding ICU admission in the same individual. 6 It relies on the assumption that all individuals could conceivably be cared for in either ICU or non-icu setting. Practically, the technique involves weighting observations by the inverse of a function of their probability of ICU admission, and then performing weighted regression. Conceptually, to estimate the IPW estimate, the propensity score was first generated, the probability of ICU admission was determined using a logistic regression model including observed patient and hospital covariates. After evaluating covariate balance and propensity score distribution overlap across ICU admission status, weights for each patient were generated. Weights for patients admitted to the ICU were calculated as the reciprocal of their probability of ICU admission. Weights for patients who were not admitted to the ICU were calculated as the reciprocal of one minus the probability of ICU admission. Thus, exposed individuals who have a high probability of exposure are weighted less than those who have a small probability of exposure. Finally, a weighted linear regression was performed to estimate the effect of ICU admission on 30-day mortality. The preceding sequence of steps was implemented in Stata s teffects command.

etable 8. Elixhauser comorbidities by ICU admission ICU Patients No. (%) Ward Patients No. (%) No. Patients 328,404 783,990 Congestive Heart Failure 122,197 (37.2) 198,736 (25.4) Valvular Disease 11,810 (3.6) 39,789 (5.1) Pulmonary Circulation Disorders 19,387 (5.9) 32,897 (4.2) Peripheral Vascular Disorders 11,782 (3.6) 38,810 (5.0) Hypertension 110,209 (33.6) 456,915 (58.3) Paralysis 11,499 (3.5) 19,664 (2.5) Other Neurological Disorders 14,440 (4.4) 53,441 (6.8) Chronic Pulmonary Disease 118,865 (36.2) 318,779 (40.7) Uncomplicated Diabetes 44,722 (13.6) 166,175 (21.2) Complicated Diabetes 5,971 (1.8) 20,464 (2.6) Hypothyroidism 17,587 (5.4) 103,662 (13.2) Renal Failure 49,901 (15.2) 128,400 (16.4) Liver Disease 2,374 (0.7) 6,967 (0.9) Peptic Ulcer Disease 64 (0.02) 117 (0.01) AIDS 201 (0.1) 348 (0.04) Lymphoma 6,776 (2.1) 15,475 (2.0) Metastatic Cancer 13,024 (4.0) 27,268 (3.5) Solid Tumor 13,825 (4.2) 31,921 (4.1) Collagen Vascular Disease 5,320 (1.6) 25,746 (3.3) Coagulopathy 21,137 (6.4) 28,855 (3.7) Obesity 8,090 (2.5) 25,343 (3.2) Weight Loss 47,504 (14.5) 58,418 (7.5) Fluid and Electrolyte Disorders 143,603 (43.7) 264,110 (33.7) Blood Loss Anemia 1,150 (0.4) 3,490 (0.5) Deficiency Anemias 31,810 (9.7) 141,701 (18.1) Alcohol Abuse 876 (0.3) 1,730 (0.2) Drug Abuse 272 (0.1) 595 (0.1) Psychoses 5,139 (1.6) 17.755 (2.3) Depression 8,435 (2.6) 57,376 (7.3)

etable 9. Instrument variable analysis model results for 30-day mortality R-squared for model = 0.22 30-Day Mortality Beta 95% Conf. Interval P value ICU -0.057-0.106, -0.009 0.02 Age 75-84 years 0.050 0.048, 0.052 < 0.001 > 85 years 0.123 0.12, 0.126 < 0.001 Sex -0.007-0.008, -0.005 < 0.001 Race Black -0.021-0.024, -0.018 < 0.001 Other -0.018-0.022, -0.014 < 0.001 Admission Source Emergency department 0.042 0.039, 0.045 < 0.001 Urbanicity Large Suburban Metropolitan 0.005 0.001, 0.009 0.01 Medium Metropolitan 0.006 0.001, 0.01 0.01 Small Metropolitan 0.006 0.001, 0.011 0.02 Micropolitan 0.013 0.008, 0.017 < 0.001 Noncore 0.014 0.009, 0.019 < 0.001 Median Income by Categories Median Income $40,000-$100,000-0.002-0.005, -0.0001 0.04 Median Income > $100,000-0.002-0.006, 0.002 0.34 Angus Organ Failure Score 1 0.058 0.051, 0.065 < 0.001 2 0.109 0.098, 0.121 < 0.001 3 0.130 0.121, 0.139 < 0.001 4 0.220 0.206, 0.233 < 0.001 > 5 0.312 0.284, 0.34 < 0.001 Elixhauser Comorbidities Congestive Heart Failure 0.011 0.008, 0.015 < 0.001 Valvular Disease -0.016-0.019, -0.013 < 0.001 Pulmonary Circulation Disorders 0.007 0.004, 0.011 < 0.001 Peripheral Vascular Disorders 0.007 0.004, 0.01 < 0.001 Hypertension -0.040-0.042, -0.037 < 0.001 Paralysis 0.021 0.016, 0.026 < 0.001 Other Neurological Disorders 0.013 0.01, 0.015 < 0.001 Chronic Pulmonary Disease -0.043-0.045, -0.041 < 0.001 Uncomplicated Diabetes -0.017-0.019, -0.015 < 0.001 Complicated Diabetes -0.034-0.038, -0.031 < 0.001 Hypothyroidism -0.022-0.024, -0.02 < 0.001 Renal Failure 0.021 0.019, 0.023 < 0.001 Liver Disease 0.046 0.039, 0.053 < 0.001 Peptic Ulcer Disease 0.004-0.048, 0.056 0.88 AIDS 0.022-0.008, 0.052 0.15 Lymphoma 0.050 0.045, 0.056 < 0.001 Metastatic Cancer 0.279 0.274, 0.285 < 0.001 Solid Tumor 0.136 0.131, 0.14 < 0.001 Collagen Vascular Disease -0.012-0.015, -0.009 < 0.001 Coagulopathy -0.021-0.026, -0.017 < 0.001 Obesity -0.037-0.04, -0.034 < 0.001 Weight Loss 0.073 0.069, 0.077 < 0.001 Fluid and Electrolyte Disorders 0.024 0.022, 0.026 < 0.001 Blood Loss Anemia -0.023-0.033, -0.013 < 0.001 Deficiency Anemias -0.026-0.028, -0.024 < 0.001 Alcohol Abuse -0.016-0.028, -0.004 0.01 Drug Abuse -0.045-0.064, -0.026 < 0.001 Psychoses -0.017-0.021, -0.013 < 0.001 Depression -0.013-0.015, -0.01 < 0.001 Mechanical ventilation 0.110 0.093, 0.127 < 0.001 Cardiopulmonary resuscitation 0.355 0.346, 0.365 < 0.001 Respiratory failure 0.140 0.129, 0.15 < 0.001 Sepsis 0.081 0.074, 0.087 < 0.001 Shock 0.086 0.076, 0.097 < 0.001

30-Day Mortality Beta 95% Conf. Interval P value Arrest 0.163 0.151, 0.175 < 0.001 Type of Pneumonia Viral Pneumonia -0.052-0.058, -0.046 < 0.001 Bacterial Pneumonia -0.053-0.056, -0.05 < 0.001 Region Mid-Atlantic 0.009 0.002, 0.015 0.01 South Atlantic 0.016 0.01, 0.022 < 0.001 East North Central 0.010 0.004, 0.016 0.001 East South Central 0.026 0.019, 0.033 < 0.001 West North Central -0.0001-0.008, 0.007 0.98 West South Central 0.020 0.013, 0.027 < 0.001 Mountain 0.003-0.007, 0.013 0.54 Pacific -0.001-0.008, 0.007 0.86 Hospital Ownership Type For-profit 0.004 0.0003, 0.008 0.03 Government 0.004-0.00001, 0.008 0.05 Hospital Teaching Status (Ratio of Resident FTE to Hospital Beds) -0.011-0.02, -0.002 0.02 Hospital Size by Beds, per 100 Beds 0.001 0.00007, 0.003 0.04 ICU Size by Proportion of Hospital Beds 5-10% 0.005 0.001, 0.01 0.03 > 10% 0.007 0.002, 0.012 0.01 Proportion of Medicaid Patients Served, per Hospital Admission 0.027-0.005, 0.058 0.10 Hospital Technology Index a -0.0002-0.0004, -0.00006 0.01 Hospital Nursing Ratio, Nurse FTE per 1,000 Patient-Days -0.003-0.005, -0.002 < 0.001 Hospital Annual Pneumonia Case Volume, per 100 Cases -0.007-0.009, -0.005 < 0.001 Year of Admission 2011 0.008 0.005, 0.01 < 0.001 2012 0.003 0.001, 0.006 0.004 Constant 0.042 0.031, 0.052 < 0.001 a The technology index is a weighted sum of the following hospital capabilities: obstetrics, medical/surgical intensive care unit, cardiac intensive care unit, emergency department, trauma center, open heart surgery, radiation therapy, computed tomography, diagnostic radiology, magnetic resonance imaging, positron-emission tomography, single-photon emission computed tomography, ultrasonography, and transplantation service. The beta for technology index represents change in one unit of the technology index per one unit change of the outcome.

etable 10. Instrument variable analysis model results for Medicare spending R-squared for model = 0.34 Medicare Spending Beta 95% Conf. Interval P value ICU -1320-3420.7, 781 0.22 Age 75-84 years -496-573.7, -419.2 < 0.001 > 85 years -1261-1402.5, -1118.6 < 0.001 Sex 222 174.9, 269.8 < 0.001 Race Black 1355 1120.4, 1590 < 0.001 Other 1455 1224.1, 1685.7 < 0.001 Admission Source Emergency department -74-189.3, 41.8 0.21 Urbanicity Large Suburban Metropolitan -1099-1384.8, -812.4 < 0.001 Medium Metropolitan -1914-2224.1, -1603.3 < 0.001 Small Metropolitan -1640-1945.1, -1335.8 < 0.001 Micropolitan -1654-1934.2, -1374.6 < 0.001 Noncore -1488-1767.4, -1208 < 0.001 Median Income by Categories Median Income $40,000-$100,000-115 -238.4, 9.1 0.07 Median Income > $100,000 325 122.7, 526.6 0.002 Angus Organ Failure Score 1 2351 2059.6, 2642.7 < 0.001 2 6967 6423.8, 7509.9 < 0.001 3 12159 11588.2, 12729.3 < 0.001 4 14684 13768.5, 15598.6 < 0.001 > 5 14045 12022.9, 16066.3 < 0.001 Elixhauser Comorbidities Congestive Heart Failure 427 291.4, 563.5 < 0.001 Valvular Disease -511-589.7, -432.1 < 0.001 Pulmonary Circulation Disorders 671 525.6, 816.2 < 0.001 Peripheral Vascular Disorders 432 337.3, 525.9 < 0.001 Hypertension -1143-1236.2, -1050.7 < 0.001 Paralysis 953 771.9, 1133.3 < 0.001 Other Neurological Disorders -753-818.2, -687.9 < 0.001 Chronic Pulmonary Disease -1098-1163.4, -1031.9 < 0.001 Uncomplicated Diabetes -770-826.3, -713.7 < 0.001 Complicated Diabetes -642-757, -527.3 < 0.001 Hypothyroidism -515-571, -459 < 0.001 Renal Failure 605 533.2, 676.5 < 0.001 Liver Disease -289-515.6, -62 0.01 Peptic Ulcer Disease 1663-785.1, 4112 0.18 AIDS 2943 1396.2, 4489.2 < 0.001 Lymphoma 46-160, 252.4 0.66 Metastatic Cancer -233-364, -102.4 < 0.001 Solid Tumor 28-86.9, 142.2 0.64 Collagen Vascular Disease -610-688.1, -532.9 < 0.001 Coagulopathy -1728-1939.3, -1516 < 0.001 Obesity -708-805.5, -610.8 < 0.001 Weight Loss 2665 2404.9, 2924.9 < 0.001 Fluid and Electrolyte Disorders -247-322, -171.5 < 0.001 Blood Loss Anemia 395 183.9, 605.3 < 0.001 Deficiency Anemias -591-657.2, -524.5 < 0.001 Alcohol Abuse -365-739.1, 9.9 0.06 Drug Abuse -1084-1630.1, -538.5 < 0.001 Psychoses -325-449.6, -201.2 < 0.001 Depression -609-682.8, -534.9 < 0.001 Mechanical ventilation 8016 7239.1, 8792.3 < 0.001 Cardiopulmonary resuscitation -3946-4453.1, -3439.5 < 0.001 Respiratory failure 3203 2749.7, 3656.8 < 0.001 Sepsis 3490 3237.7, 3742.8 < 0.001 Shock -266-748.4, 215.7 0.28

Medicare Spending Beta 95% Conf. Interval P value Arrest 2349 1815.6, 2882.9 < 0.001 Type of Pneumonia Viral Pneumonia 265 28.9, 501.8 0.03 Bacterial Pneumonia 3305 3113.7, 3495.6 < 0.001 Region Mid-Atlantic 451 17.6, 883.7 0.04 South Atlantic -1417-1773.4, -1059.6 < 0.001 East North Central -1328-1639.9, -1016.1 < 0.001 East South Central -1858-2210.6, -1506.1 < 0.001 West North Central -1117-1482.3, -752.5 < 0.001 West South Central -1977-2341.7, -1612 < 0.001 Mountain -1057-1505.4, -609.4 < 0.001 Pacific 1533 990.2, 2076.6 < 0.001 Hospital Ownership Type For-profit -64-292.2, 164.4 0.58 Government 419 133.7, 705.3 0.004 Hospital Teaching Status (Ratio of Resident FTE to Hospital Beds) 3534 2641, 4426.2 < 0.001 Hospital Size by Beds, per 100 Beds 64-28, 155 0.18 ICU Size by Proportion of Hospital Beds 5-10% -239-557.6, 80.6 0.14 > 10% -312-618.9, -5.3 0.05 Proportion of Medicaid Patients Served, per Hospital Admission 22154 18990.7, 25317 < 0.001 Hospital Technology Index a -3-13.2, 7 0.54 Hospital Nursing Ratio, Nurse FTE per 1,000 Patient-Days -57-127.3, 13.9 0.12 Hospital Annual Pneumonia Case Volume, per 100 Cases 9-149, 131 0.90 Year of Admission 2011 22-61.5, 106.3 0.60 2012-42 -139, 54.4 0.39 Constant 7506 6851.8, 8159.8 < 0.001 a The technology index is a weighted sum of the following hospital capabilities: obstetrics, medical/surgical intensive care unit, cardiac intensive care unit, emergency department, trauma center, open heart surgery, radiation therapy, computed tomography, diagnostic radiology, magnetic resonance imaging, positron-emission tomography, single-photon emission computed tomography, ultrasonography, and transplantation service. The beta for technology index represents change in one unit of the technology index per one unit change of the outcome.

etable 11. Instrument variable analysis model results for hospital costs R-squared for model = 0.32 Hospital Costs Beta 95% Conf. Interval P value ICU 2842-167.8, 5850.8 0.06 Age 75-84 years -1038-1144.3, -931 < 0.001 > 85 years -2443-2645.9, -2240.4 < 0.001 Sex 310 249.9, 371.1 < 0.001 Race Black 830 502.9, 1157.2 < 0.001 Other 954 645.2, 1262.4 < 0.001 Admission Source Emergency department -378-518.3, -237.1 < 0.001 Urbanicity Large Suburban Metropolitan -599-1014.7, -184.1 0.01 Medium Metropolitan -1161-1643.6, -677.4 < 0.001 Small Metropolitan -1149-1611.9, -685.5 < 0.001 Micropolitan -1109-1511, -707.3 < 0.001 Noncore -896-1305.2, -486.9 < 0.001 Median Income by Categories Median Income $40,000-$100,000 387 223, 550.8 < 0.001 Median Income > $100,000 1183 861.7, 1504.9 < 0.001 Angus Organ Failure Score 1 2211 1809.2, 2613.4 < 0.001 2 6867 6161.5, 7572.2 < 0.001 3 12305 11670.5, 12939.3 < 0.001 4 15284 14219.6, 16347.9 < 0.001 > 5 13612 11284.3, 15938.8 < 0.001 Elixhauser Comorbidities Congestive Heart Failure 922 723.3, 1120.6 < 0.001 Valvular Disease -731-833.7, -628.7 < 0.001 Pulmonary Circulation Disorders 1187 1006.7, 1366.6 < 0.001 Peripheral Vascular Disorders 278 160.5, 396 < 0.001 Hypertension -1708-1824.2, -1591 < 0.001 Paralysis 896 665.8, 1125.6 < 0.001 Other Neurological Disorders -1022-1106.4, -938.1 < 0.001 Chronic Pulmonary Disease -1194-1272, -1115.4 < 0.001 Uncomplicated Diabetes -1209-1279.1, -1138.5 < 0.001 Complicated Diabetes -986-1132.8, -838.7 < 0.001 Hypothyroidism -835-909.4, -761.1 < 0.001 Renal Failure 771 666.9, 876 < 0.001 Liver Disease -360-660.7, -58.7 0.02 Peptic Ulcer Disease 4319 1270.6, 7368.2 0.01 AIDS 772-742.5, 2287.1 0.32 Lymphoma 766 466, 1066.8 < 0.001 Metastatic Cancer -589-753.8, -425 < 0.001 Solid Tumor -116-257.7, 26.5 0.11 Collagen Vascular Disease -898-1000.9, -795.3 < 0.001 Coagulopathy -990-1242.8, -736.5 < 0.001 Obesity -726-843.8, -607.6 < 0.001 Weight Loss 3876 3493.6, 4259.4 < 0.001 Fluid and Electrolyte Disorders -164-258.5, -69 0.001 Blood Loss Anemia 1159 884.3, 1433.8 < 0.001 Deficiency Anemias -622-709.1, -534.3 < 0.001 Alcohol Abuse -194-635.8, 246.9 0.39 Drug Abuse -1047-1856.3, -236.8 0.01 Psychoses -476-625.8, -325.7 < 0.001 Depression -804-904.4, -703.5 < 0.001 Mechanical ventilation 7887 6843, 8931.6 < 0.001 Cardiopulmonary resuscitation -7128-7727.2, -6528.1 < 0.001 Respiratory failure 3052 2418.7, 3685.9 < 0.001 Sepsis 233-126.6, 593.4 0.20 Shock 1766 1093.1, 2438.3 < 0.001

Hospital Costs Beta 95% Conf. Interval P value Arrest 725 15.5, 1434 0.05 Type of Pneumonia Viral Pneumonia 1382 1089.1, 1675.9 < 0.001 Bacterial Pneumonia 4213 3949.8, 4476.2 < 0.001 Region Mid-Atlantic 514-243.7, 1270.9 0.18 South Atlantic -1344-1988.1, -700 < 0.001 East North Central -957-1588.4, -325.1 0.003 East South Central -1760-2448.3, -1072.6 < 0.001 West North Central -640-1352.8, 72.3 0.08 West South Central -1474-2173.1, -775.4 < 0.001 Mountain -590-1385.6, 205.1 0.15 Pacific 3240 2271.8, 4208.8 < 0.001 Hospital Ownership Type For-profit 320-48.7, 689.3 0.09 Government 333-63.1, 728.9 0.10 Hospital Teaching Status (Ratio of Resident FTE to Hospital Beds) 1264-60.2, 2588.4 0.06 Hospital Size by Beds, per 100 Beds 71-31, 269 0.12 ICU Size by Proportion of Hospital Beds 5-10% -90-484.3, 303.9 0.65 > 10% -261-681, 159.1 0.22 Proportion of Medicaid Patients Served, per Hospital Admission 8765 3695.3, 13835.2 0.001 Hospital Technology Index a 5-9.2, 19.3 0.48 Hospital Nursing Ratio, Nurse FTE per 1,000 Patient-Days 361 251.2, 470.2 < 0.001 Hospital Annual Pneumonia Case Volume, per 100 Cases -119-282, 140 0.51 Year of Admission 2011-29 -138.2, 79.5 0.60 2012-26 -154.3, 102.6 0.69 Constant 7250 6266.2, 8233.7 < 0.001 a The technology index is a weighted sum of the following hospital capabilities: obstetrics, medical/surgical intensive care unit, cardiac intensive care unit, emergency department, trauma center, open heart surgery, radiation therapy, computed tomography, diagnostic radiology, magnetic resonance imaging, positron-emission tomography, single-photon emission computed tomography, ultrasonography, and transplantation service. The beta for technology index represents change in one unit of the technology index per one unit change of the outcome.

etable 12. Instrumental variable analysis on costs per patient by in-hospital mortality Instrumental Variable Adjusted Medicare Payments per Patient Stratified by Survival Model a ICU Ward Absolute difference (95% CI) P value Patients Patients Surviving Patients $8,736 $10,165 -$1,429 (-3294, 436) 0.13 Deceased Patients $20,534 $18,359 $2,175 (-3302, 7651) 0.44 Instrumental Variable Adjusted Hospital Costs per Patient Stratified by Survival Model a ICU Ward Absolute difference (95% CI) P value Patients Patients Surviving Patients $13,057 $10,653 $2,404 (-395, 5204) 0.09 Deceased Patients $22,013 $15,531 $6,482 (-784, 13748) 0.08 a 2-stage least squared regression of all patients using differential distance to nearest high-icu use hospital as instrumental variable, adjusted for all variables in tables 1 and 2. All 29 Elixhauser comorbidities were included in models individually. Angus organ failure score, which identifies severity of illness by patient organ failures derived from the administrative record with a maximum score of six (higher scores indicate more organ failures), was defined to include all organ failures numbered 0 to > 5. Hospital region included the nine regions by U.S. census definitions. All models included clustering of patients within hospitals.

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