APPENDIX. Supplemental Methods 2. Supplemental Exhibit S1 11. Supplemental Exhibit S2 13. Supplemental Exhibit S3 14. Supplemental References 15

Transcription

1 Knowlton K, Rotkin-Ellman M, Geballe L, Max W, Solomon GM. Six climate change related events in the United States accounted for about $14 billion in lost lives and health costs. Health Aff (Millwood). 2011;30(11). APPENDIX Table of Contents Supplemental Methods 2 Supplemental Exhibit S1 11 Supplemental Exhibit S2 13 Supplemental Exhibit S3 14 Supplemental References 15 1

2 Supplemental Methods Air Quality: National ozone air pollution Hubbell et al. (2005) 1 includes hospitalization incidence for respiratory diseases only for children younger than 2 years and adults ages 65 years or older. Individuals in these age groups are assumed to bear no work productivity loss, so the COI estimates associated with hospitalization include only medical costs. Healthcare Cost and Utilization Project (HCUP) cost data are charted by age group, but cost data for children younger than 2 are not provided. Thus, average medical expenses for respiratory diseases for children younger than 1 are assumed to be applicable to children younger than 2 years of age. Furthermore, the incidence study does not provide International Classification of Diseases, Ninth Revision (ICD-9) codes for the illnesses examined; instead health data are reported for the general category of respiratory symptoms. 1 We assumed that the average medical cost data for the Major Diagnostic Category (MDC) Respiratory Diseases available on the Healthcare Cost and Utilization Project website (HCUPnet) are most applicable. 2

3 Sensitivity Analysis Hubbell et al. (2005) 1 reports hospitalizations for all respiratory diseases, but emergency department(ed) visits only for asthma. To estimate how much of an undercounting this could be, we use the average Medical Expenditure Panel Survey (MEPS) hospitalization-to-ed visit ratio for condition categories chronic obstructive pulmonary disease (COPD), asthma and pneumonia to infer total respiratory-related ED visit incidence. We would also have liked to include an estimate of ozone-related morbidity from respiratory disease in individuals between the ages of 2-65, but national data were not available to allow such an estimate. Since the Hubbell et al. (2005) 1 paper was published there have been a number of studies identifying significant health impacts associated with lower ambient ozone levels. 2 Based on this new science, the US Environmental Protection Agency (EPA) is currently reviewing the standard and has evaluated the potential health benefits of a 60 parts per billion (ppb) ozone level. To estimate the degree to which this change in the standard would influence our cost analysis, we used EPA s published estimate of increased premature mortality associated with ozone levels greater than 60 ppb during the high-ozone season (April- September) of 2002 and 2004 in 12 US cities that represent 40% 3

4 of the country s overall urban population (Atlanta, Boston, Chicago, Cleveland, Detroit, Houston, Los Angeles, New York, Philadelphia, Sacramento, St. Louis, Washington, D.C.). In this study, city-specific ozone dose-response relationships were applied to estimate ozone health effects. 3 Health effects were calculated as the difference between those under recent air quality conditions vs. those effects estimated when just-meeting the existing and/or proposed new standards (i.e. the health impacts attributable to unhealthy ozone levels defined as an exceedance of a standard). The possible interactive effects of heat and ozone air pollution, which could potentially increase mortality and morbidity, were not evaluated. Rather, each was considered separately in this analysis. Using these data we calculate the total ozone-associated premature mortality in the 12 cities, the associated costs, and the population-normalized mortality and cost rates. To explore how large the impact might be if these city specific estimates were applied across the country we multiplied the incidence and cost rates to the population in the counties projected by EPA to not attain the 60 ppb standard. 3 Heat Wave: 2006 California Heat Wave MEPS does not include health costs for heat-related illnesses at a level of specificity to adequately capture the impacts of 4

5 extreme heat. The diagnostic condition categories that include the pertinent ICD-9 codes are general groupings that encompass diseases of greater severity, and therefore cost, than those caused by extreme heat. ICD-9 codes 276, , and 992 are encompassed by MEPS condition categories Other endocrine, nutritional and immune disorder, Kidney problems, and Trauma-related disorders. Thus, to avoid overestimating costs, the MEPS hospitalization-to-outpatient and -home health visit, and -prescribed medicine ratios for the category all conditions are used to infer the incidence rates. The average cost of these MEPS inferred incidences are based on the average cost of all conditions weighted by the number of reported incidences for each health endpoint. Hurricane: 2004 Florida Hurricane Season The outpatient, home health visit, and prescribed medicine usage rates for carbon monoxide (CO) poisoning are inferred by using a MEPS hospitalization-to-outpatient visit ratio for the MEPS diagnostic condition category Poisoning by medical and nonmedical substances, which in the MEPS dataset includes the relevant ICD-9 code 986 for CO poisoning. The study upon which we rely for health endpoint incidence rates for people affected by PTSD as a result of hurricane exposure does not indicate the number of PTSD sufferers who sought treatment for the illness, 5

6 which is necessary to calculate health costs using the COI approach. However, Greenberg et al. (1999) 4 reports healthcare service utilization rates for people suffering from anxiety disorders, which encompasses post-traumatic stress disorder (PTSD). 4 Applying the hospitalization and outpatient service utilization rates from the latter study to the number of PTSD sufferers reported in the former study, we estimated incidence for hospitalizations and outpatient visits. Greenberg et al. (1999) 4 does not report a utilization rate for all outpatient services; rather, rates for various types of outpatient services are listed. An average of all the outpatient service utilization rates is assumed, as a single category of services. No ED service utilization rate for anxiety disorder sufferers is reported in Greenberg et al. (1999), 4 thus the ED visit incidence rate is inferred by using the MEPS hospitalization-to-ed visit ratio. The cost of PTSD-related hospitalizations is based on HCUP weighted average length of stay and medical charges for ICD-9 code , the diagnosis for PTSD. For the year 2004, average lengths of stay and medical charges for ICD-9 code are listed for the time period before and after October 1, Thus, the average length of stay and medical charges are based on an average of the Healthcare Cost and Utilization Project (HCUP) estimates before and after October 1, 2004, weighted by the number of discharges. 6

7 Sensitivity Analysis Our baseline mental health cost estimates resulting from the 2004 Florida hurricane season are based on the Greenberg et al. (1999) 4 reported healthcare service utilization rates for anxiety disorder sufferers and HCUP and MEPS average medical cost data. An alternative method involves applying the average direct medical costs per anxiety sufferer of $3,000 as reported by Greenberg et al. (1999) 4 to all 104,000 reported incidences of PTSD resulting after the 2004 Florida hurricanes. This cost estimate of PTSD does not include the indirect cost of lost work productivity, which is included in traditional Cost of Illness (COI) approach estimates, but it does incorporate a broader spectrum of utilized healthcare services, including social services and primary care. We would have liked to include an estimate of injuries associated with the Florida hurricanes, but were unable to identify a dataset that would allow us to construct a reliable estimate. Infectious Disease: 2002 West Nile virus outbreak in Louisiana Zohrabian et al. (2004) 5 reports hospitalizations for a general category of Central Nervous System Illnesses, instead of by specific ICD-9 code, for identified West Nile Virus cases. West Nile Virus infections are classified under ICD-9 code

8 The Louisiana WNV outbreak occurred in 2002, but the 2002 HCUP data for ICD-9 code do not include a sample size large enough for meaningful statistics, so 2003 cost data for ICD-9 code are applied. ED visits attributable to this event are also not reported by ICD-9 code, thus the average medical expenses for all categories of ED visits is applied. MEPS average medical expense data for the condition category Infectious diseases, which encompasses ICD-9 code 066.4, are used to estimate the cost of outpatient, home health visits, and prescribed medicines. Sensitivity Analysis For our baseline estimate of costs associated with the WNV outbreak in Louisiana we relied on a study (Zohrabian et al. 2004) 5 that did not directly report the number of ED visits. To estimate this impact, we extrapolated ED visits based on use of emergency services reported in the study for those patients who were hospitalized. Therefore, our baseline estimate does not incorporate those individuals who may have sought treatment in an ED but were not hospitalized. For comparison, we inferred the number of ED visits based on the number of hospitalizations reported in the study and the hospitalization-to-ed visit ratio for the MEPS condition category Infectious disease. 8

9 River Flooding: 2009 Red River Floods, North Dakota No 2009 health cost data were available at the time of analysis, so all costs are based on the 2007 MEPS data. ED visit costs are based on the average medical cost weighted by the number of discharges for all conditions. The MEPS condition category Trauma-related disorders is used to infer hospitalization, outpatient and home health visit, and prescribed medicine usage rates. MEPS data do not include average length of hospital stay data, so the COI hospitalization estimate does not include lost work productivity costs. Wildfire: 2003 Southern California Wildfires Sensitivity Analysis In the Delfino et al. (2009) 6 analysis of morbidity impacts from smoke resulting from the 2003 Southern California wildfires, there is a calculation of a 95% confidence interval for hospitalizations due to asthma and pneumonia. To explore the range of estimates represented in this study, we calculated the lower and upper bound costs by applying this confidence interval. Health Costs Methods Sensitivity Analysis 9

10 To examine the variability associated with methods for valuing morbidity we compared the results of the COI approach to that generated by a Willingness to Pay (WTP) methodology. WTP methods, which are based on the maximum amount people are willing to pay to avoid certain health outcomes, better captures the costs of pain and suffering associated with illnesses and have been incorporated into governmental and academic health valuation studies of environmental phenomena. 7 8 According to the EPA Handbook for Non-Cancer Health Effects Valuation, WTP estimates can be inferred from COI estimates using a WTP/COI ratio. WTP/COI ratios between 1.5 and 3.0 are most common. We therefore used 1.5 as the lower and 3.0 as the upper bound to generate a range of costs. Although a point estimate was used to calculate costs associated with mortality impacts, EPA s recommended VSL is the mean of a probability distribution fit to twenty-six published Value of a Statistical Life (VSL) estimates. To better reflect this variability in VSL estimates, we calculated mortality costs using the range ( million in 2008 dollars) of the 26 studies

11 Supplemental Exhibit(s) Supplemental Exhibit S1. Incidence data sources and methodology Climate- Incidence found in epidemiologic Inferred incidence sensitive literature Stressor Health outcome Source Health service Method Air Quality Premature death, Hubbell et al. Outpatient visit, MEPS Hospitalization- Ozone Hospitalization 2005 Home health visit, to-outpatient visit, (Nationwide) (respiratory, ages Prescribed -Home health visit, younger than 2 and 65 medicine -Prescribed Medicine and older only), ED weighted average ratios visit (asthma only) for condition categories COPD, asthma, and Pneumonia (0.0255, , ) Heat Wave Premature death Hoshiko et Outpatient visit, MEPS Hospitalization- (California) al Home health to-outpatient visit, Hospitalization, ED Knowlton et visit, Prescribed -Home health visit, visit al medicine -Prescribed Medicine ratios for all conditions (0.0189, , ) Hurricane Premature death Ragan et Outpatient visit, MEPS Hospitalization- (Florida) al Home health to-outpatient visit, visit, Prescribed Hospitalization, ED Sniffen et medicine -Home health visit, Visit (CO poisoning al (CO poisoning) -Prescribed Medicine only) ratios for all condition medical and nonmedical substance (0.0865, 53.6, ) Hospitalization, Hurricane-related PTSD Outpatient visit (PTSD) ED visit, Home health visit, Prescribed medicine (PTSD) incidence (Acierno et al. 2007) X Healthcare utilization rate (Greenberg et al. 1999) MEPS Hospitalizationto-ED visit, -Home health visit, -Prescribed medicine ratios for condition category Mental disorders (0.8856, , ) West Nile Premature death, Zohrabian et Home health visit, MEPS Hospitalization- Virus Hospitalization, al Prescribed to-home health visit, (Louisiana) ED visit, Outpatient medicine -Prescribed medicine 11

12 visit ratios for condition category Infectious disease (1.2896, ) River Premature death, ED State Hospitalization, MEPS ED visit-to- Flooding visit Surveillance Outpatient visit, Hospitalization, - (North Home health visit, Outpatient Dakota) Prescribed visit, -Home health medicine visit, -Prescribed medicine ratio for condition category Trauma-related disorders (6.1469, , , ) Wildfire Premature deaths (fire Office of Premature deaths HCUP Hospitalization- (Southern and mudslide) Emergency (air quality) to-death ratios for California) Services asthma (.0046) and 2004 pneumonia (.061) Hospitalizations Delfino et al. ED visit, MEPS Hospitalization- (asthma and 2009 Outpatient visit, to-ed visit, -Outpatient pneumonia) Home health visit, visit,-home health visit, Prescribed medicine (asthma and pneumonia) -Prescribed medicine ratios for condition categories COPD, asthma (0.3855, , , ) and Pneumonia (0.7534, , 5.036, ) 12

13 Supplemental Exhibit S2. Cost per incident, healthcare service Health Endpoint Home Climate-sensitive ED Outpatient health Prescribed stressors Hospitalization visit visit visit medicine (U.S dollars per incidence) Air Quality Ozone Asthma-related $ a $ 648 c $ $ $ Respiratory Disease, ages younger than 2 6,299 a 514 c 7,633 c 419 c Respiratory Disease, ages 65 and older 11, c 7,633 c 419 c Heat Wave Electrolyte Imbalance 14,998 b 914 c 5,858 c 581 c Acute Renal Failure 21,069 b 914 c 5,858 c 581 c Nephritis 22,567 b 914 c 5,858 c 581 c Heat-related 11,343 b 914 c 5,858 c 581 c All Causes 873 d Hurricane CO poisoning 10,726 b 669 c 191 c 82 c 92 c PTSD 8,352 b 1,725 c 849 c 7,051 c 859 c Infectious Disease West Nile Virus 63,435 b 768 c 321 c 13,812 c 479 c River Flooding All Causes 19,617 c 881 d 1,230 c 4,615 c 125 c Wildfire Asthma 9,270 b 795 c 404 c 4,779 c 469 c Pneumonia 15,213 b 653 c 381 c 2,970 c 134 c Key a = HCUP by Major Diagnostic Category b = HCUP by ICD-9 code c = MEPS by Condition Category d = MEPS for all ED visits 13

14 Supplemental Exhibit S3. Sensitivity analysis results Climate-related Cost Total cost change health stressor Health endpoint change (Thousand US (+ or -) 2008 Dollars) Air Quality Ozone Emergency Department visit + $5,237 Air Quality Ozone Mortality + 1,763,348 Hurricane Post Traumatic Stress Disorder + 57,119 morbidity West Nile Virus Emergency Department visit Wildfire Hospitalization +/- (a) 8,567 Total Case Study Specific Adjustments + $1,816,656 - $1,833,791 Morbidity Cost Method Adjustment + $372,122 - $1,488,488 Mortality Cost Method Adjustment - $11,823,000 + $22,294,800 Total Sensitivity Analysis Adjustment Range - $9,634,222 + $25,617,079 (a) Wildfire cost change is +/- with a 95% upper and lower confidence interval range of costs applied. 14

15 1 Hubbell BJ, Hallberg A, McCubbin DR, Post E. Health-related benefits of attaining the 8-hr ozone standard. Environ Health Perspect. 2005; 113(1): Bell ML, Peng RD, Dominici F. The exposure-response curve for ozone and risk of mortality and the adequacy of current ozone regulations. Environ Health Perspect. 2006; 114: United States Environmental Protection Agency, Office of Air Quality Planning and Standards. Review of the National Ambient Air Quality Standards for ozone: policy assessment of scientific and technical information. 2007; Staff Paper #452/R Greenberg PE, Sisitsky T, Kessler RC, Finkelstein SN, Berndt ER, Davidson JRT, Ballenger JC, et al. The economic burden of anxiety disorders in the 1990s. J Psych. 1999; 60(7): Zohrabian A, Meltzer MI, Ratard R, Billah K, Molinari N, Roy K, et al. West Nile virus economic impact, Louisiana, Emerg Infect Diseases. 2004; 10(10): Delfino RJ, Brummel S, Wu J, Stern H, Ostro B, Lispett M. The relationship of respiratory and cardiovascular hospital admissions to the southern California wildfires of Occup Environ Med. 2009; 66: Thayer M, Chestnut L, Stephen VDE. The economic value of respiratory and cardiovascular hospitalizations, prepared for the California Air Resources Board and California Environmental Protection Agency United States Environmental Protection Agency (homepage on the Internet). National Center for Environmental Economics. An experiment in determining Willingness to Pay for national water quality. 2010; Available from: 15

16 44d0053bec2!OpenDocument. 9 Alberini A, Krupnick A. Cost-of-Illness and Willingness-to-Pay estimates of the benefits of improved air quality: evidence from Taiwan. Land Econ. 2000; 76(1): Kochi I, Loomis J, Champ P, Donovan G. Health and Economic Impact of Wildfires: Literature Review. 2008; Available from: 11 Rowe R, Chestnut L. Valuing changes in morbidity: WTP versus COI measure. Energy and Resource Consultants, Inc United States Environmental Protection Agency (homepage on the Internet). Cost of Illness Handbook, Executive Summary. 2010; Available from: 16