CONSIDERING THAT APPROXIMATELY two thirds of

Transcription

1 ORIGINAL ARTICLE Changes in Disability Following Physical Therapy Intervention for Patients With Low Back Pain: Dependence on Symptom Duration Mary Beth Badke, PT, PhD, William G. Boissonnault, PT, DHSc 749 ABSTRACT. Badke MB, Boissonnault WG. Changes in disability following physical therapy intervention for patients with low back pain: dependence on symptom duration. Arch Phys Med Rehabil 2006;87: Objectives: To assess the impact of symptom duration on functional outcome, functional improvement, pain, and patient perception of recovery after a physical therapy (PT) program for low back pain (LBP) and to determine what variables are significantly associated with improved function. Design: Retrospective case series. Setting: Outpatient setting at a tertiary care facility. Participants: Patients (N 130) who were seen for PT between June 2003 and November Interventions: A customized rehabilitation program was developed for each patient based on examination findings and included a combination of the following interventions: mobilization/manipulation, flexibility exercises, strengthening exercises, endurance exercises, massage techniques, and heat and cold modalities. Main Outcome Measures: Functional outcome, functional improvement, perceived pain, and perceived improvement scores in the CareConnections Outcomes System (formerly TAOS) database. Results: Persons whose symptom duration was greater than 6 months had significantly less functional improvement than persons whose symptom duration was less than 1 month. The median percentage improvement score for perceived recovery was also significantly lower for the chronic group than for the acute group. There was no significant difference in the percentage decrease in pain among the acute, subacute, and chronic groups. In regression analyses, a model with age (P.001), symptom duration (P.002), and inclusion of strengthening, flexibility, and mobilization and manipulation exercises (P.001) fit the data well and explained 55.5% of the variance in functional improvement score for all 3 groups combined. Conclusions: Patients showed improvements in function following a rehabilitation program for LBP. The functional improvement score is influenced by age, symptom duration, and inclusion of mobilization/manipulation and strengthening and flexibility exercises. Key Words: Manipulation therapy; Pain; Physical therapy techniques; Rehabilitation; Treatment outcome. From the Department of Orthopedics and Rehabilitation, University of Wisconsin Hospital and Clinics, Madison, WI (Badke); and Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, Madison, WI (Boissonnault). No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. Reprint requests to Mary Beth Badke, PT, PhD, Outpatient Rehabilitation Services, 6630 University Ave, Middleton, WI 53562, mb.badke@hosp.wisc.edu /06/ $32.00/0 doi: /j.apmr by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation CONSIDERING THAT APPROXIMATELY two thirds of adults experience low back pain (LBP) at some point in their life and LBP is the most common reason for work disability in the United States, 1 it is not surprising that spinal disorders are among the most frequently noted primary diagnosis associated with patient visits to physician offices. 2 The direct health care and indirect costs (eg, lost labor) associated with LBP are tremendous: billions of dollars each year. 3,4 Large percentages of these patients are seen by physical therapists for rehabilitation. Studies have consistently shown LBP being the most common reason patients seek outpatient physical therapy (PT) services. 5-7 Various interventions utilized by physical therapists for this population have been described. Jette and Jette 8 reported flexibility exercises, strengthening exercises, heat modalities, endurance exercises, and mobilization/manipulation (interchangeable terms used to describe a manual therapy technique to the joints, including thrust and nonthrust therapeutic maneuvers 9 ) being the most frequently utilized for patients with LBP. Jette and Delitto 10 listed exercise instruction, heat modalities, ultrasound, electric stimulation, and massage being the most frequently provided treatment procedures by therapists. The goal of rehabilitation in the management of patients with LBP has evolved from a primary goal of pain relief, to relief of symptoms in conjunction with restoration of function. In addition, documentation of change in level of disability is a relatively recent emphasis in the assessment of patient outcome following PT care. Investigating the attainment of these goals in therapy programs and factors that influence outcome is important, especially as an aid to predicting patient prognosis and appropriate utilization of PT resources. Few studies have investigated the impact of PT interventions on level of patient disability and the factors that may influence outcome to such care. Jette and Jette 8 reported improved physical and emotional health per the Medical Outcome Study 36-Item Short-Form Health Survey (SF-36) in patients with low back impairments following PT treatments over an episode of care. Improvement was noted in all SF-36 domains except general health perceptions. Specifically, receiving endurance exercises and not receiving heat or cold modalities were associated with better outcomes. 8 Although they provided information not previously reported, based on reported study limitations, the authors recommended future studies investigating the relation of PT intervention to health-related outcomes. Di Fabio et al 11 reported that patients with more acute LBP, without accompanying lower-extremity pain, had better functional outcomes at completion of PT care. All patients in this study were receiving workers compensation for their low back injury, which has the potential to negatively impact recovery from such injuries. 12 Finally, Ross 13 described changes in

2 750 PHYSICAL THERAPY FOR PATIENTS WITH LOW BACK PAIN, Badke Characteristics Table 1: Patient Characteristics Acute (n 27) Subacute (n 63) Chronic (n 40) Age (y) Mean SD Range Sex, n (%) Men 12 (44) 29 (46) 11 (27) Women 15 (56) 34 (54) 29 (73) Depressed, n (%) Yes 7 (26) 12 (19) 7 (18) No 20 (74) 51 (81) 33 (82) Comorbidities, n (%) (89) 52 (83) 38 (95) 2 3 (11) 11 (17) 2 (5) Smoking, n (%) Yes 2 (7) 9 (14) 1 (3) No 25 (93) 54 (86) 39 (97) Abbreviation: SD, standard deviation. Table 2: Characteristics of Treatment Program,* Utilization of Interventions, and Intensity and Duration of Care for Patients With Spinal Impairments Characteristics Acute (n 27) Subacute (n 63) Chronic (n 40) Strengthening exercises Flexibility exercises Mobilization/manipulation Endurance exercises Massage techniques Heat modalities Cold modalities No. of visits Mean SD Range Treatment duration (wk) Mean SD Range NOTE. Values are percentage or as otherwise indicated. *Percentage of patients receiving this type of treatment. disability for patients (military personnel) with LBP receiving PT care. LBP of shorter duration, not accompanied by lowerextremity symptoms, was associated with greater decreases in disability. As with the workers compensation population, questions are raised as to whether changes in military personnel can be generalized to nonmilitary populations. The purposes of this study were (1) to describe physical therapist treatment choices for patients with LBP, (2) to investigate the impact of symptom duration on functional outcome, functional improvement, pain, and perceived recovery in patients with LBP following PT care, and (3) to determine which variables were associated with enhanced function. Identifying factors associated with enhanced or reduced recovery from LBP episodes will assist clinicians in establishing a more accurate patient prognosis. METHODS Study Populations Patients. In a retrospective medical record review, we identified 133 patients seen consecutively for treatment of low back disorders between June 2002 and November 2003 at 1 of 4 University of Wisconsin Hospital and Clinics Orthopedic Outpatient sites. All subjects were classified with an International Classification of Diseases, 9th Revision 14 code of (LBP) or (sciatica) as a primary or secondary diagnosis. We divided patients into 3 groups based on their symptom duration. For the purpose of this study, per the parameters set by Ross, 13 those beginning therapy within 1 month postonset of their symptoms were defined as the acute group, those beginning therapy between 1 month and 6 months postonset were defined as the subacute group, and those beginning therapy greater than 6 months postonset were defined as the chronic group. The CareConnections Outcomes System (formerly TAOS) database contained information from patients who filled out the requisite initial and discharge questionnaires and had a completed episode of care. Three subjects with missing or incomplete data relating to the outcome variables were excluded from the study. Descriptive subject information concerning age, sex, and comorbidities is described in table 1. Three of the patients were receiving workers compensation for their back pain condition. The 3 groups were dissimilar in 3 areas: (1) the acute group was older and had a relatively higher percentage of subjects with depression, (2) the chronic group had a higher percentage of women and persons with fewer than 2 comorbidities, and (3) the subacute group had a higher percentage of persons who smoke. Physical Therapists A total of 15 physical therapists working in the 4 clinic sites provided the patient care. The average age standard deviation (SD) of the therapists was years (range, 31 55y). Sixty percent of the physical therapists were women. The highest credential of 40% of the physical therapists was a bachelor s degree. Thirteen percent had an entry-level master s degree, 40% had an advanced-level master s degree, and 1 therapist had a doctorate of science. Two physical therapists were American Physical Therapy Association (APTA) board certified in orthopedics and 2 were graduates of an APTA credentialed orthopedic clinical residency program. The average years of clinical practice were (range, 2 32). Fifty-three percent worked full-time treating an average of 40 patients a week. Interventions Table 2 shows the percentages of patients receiving various PT interventions over the treatment duration. The most frequent combinations of these treatments are shown in table 3. The number of visits ranged from 5 to 8 for each group, over a mean duration of 7.7 weeks for the acute group, 8.8 weeks for the subacute group, and 11 weeks for the chronic group. Table 3: Combinations of Treatments* for Patients With Spinal Impairments Multimodal Interventions Acute (n 27) Subacute (n 63) Chronic (n 40) Flexibility, strengthening, and mobilization/manipulation Flexibility and strengthening exercises Massage, strengthening, and mobilization/manipulation NOTE. Values are percentage. *Percentage of patients receiving this combination of exercises.

3 PHYSICAL THERAPY FOR PATIENTS WITH LOW BACK PAIN, Badke 751 Table 4: Mean Assessment Measure Values Measure Acute Subacute Chronic Initial function Functional outcome Functional improvement P NOTE. Values are mean SD. Outcome Measures The CareConnections Outcomes System was developed by Schunk and Rutt 15 to evaluate outcomes in orthopedic outpatient rehabilitation patients. The index is a self-report questionnaire designed to address activities specific to 5 anatomic areas: lumbar, lower extremity, upper extremity, cervical, and temporomandibular joint. In addition, each patient responds to 5 common areas: walking, work, personal care, sleeping, and recreation and sports. Within each section, there are 6 statements that are scored on a 0-to-5 scale from least functional to most functional. The scores for each question are added together and divided by the total number of points possible for a final score. For the purposes of this study, the lumbar portions of the CareConnections Outcomes instrument were used, which included part I and part II, groups D and F (appendix 1). Schunk and Rutt 15 examined the content validity and test-retest reliability of the CareConnections Outcomes tool. Content validity was established by a panel of experienced physical therapists that reviewed the instrument and determined that the items for each anatomic area appropriately measured the content domain. In addition, factor analysis was performed on 100 questionnaires to confirm that items under each category evaluated the same anatomic area. Discriminant analysis was used to determine how well the instrument could classify patients into categories of anatomic involvement. In the entire sample of 100 patients, 76.54% were placed in the correct group by the discriminate function. Establishment of concurrent validity is being investigated. Test-retest reliability was evaluated for each item of the CareConnections Outcomes instrument using an intraclass correlation coefficient (ICC) (model 3,1). Values ranged from.69 to.96 with a mean ICC of.85. We administered the CareConnections Outcomes tool during the initial PT visit, and again at discharge. Functional outcome, functional improvement, perceived pain, and perceived improvement were scored by an office worker and transferred to the outcomes database along with acuity, utilization, and work status information. Functional improvement was defined as the difference between the functional score at the initial visit and the functional score at discharge. Functional outcome was defined as the functional score at discharge. Perceived pain and perceived improvement were measured with a ruler on a visual analog scale (VAS). The pain index ranged from no pain to the worst pain imaginable in the last 24 hours. The improvement index was only assessed once at the completion of therapy and ranged between no improvement and complete recovery since the beginning of therapy treatment. The raw score is the number on the ruler in centimeters, which corresponded to the patient s mark. The pain score was converted into a percentage with the following formula: percentage decrease in pain (initial pain final pain)/initial pain. In the acute pain setting, the test-retest reliability and validity of the VAS has been established. The repeatability of the VAS is good, as can be seen by correlation coefficients ranging from.97 to ,17 Data Analysis Descriptive statistics for the functional outcome, functional improvement, pain, and perceived improvement scores were calculated for each group. Scores before and after PT on the functional outcome and pain scores were compared within groups using the Wilcoxon matched-pair signed-rank test. Pretherapy to posttherapy differences were compared between the groups using a Kruskal-Wallis 1-way analysis of variance (ANOVA) by ranks. Post hoc analysis assessed pairwise differences between (1) acute and subacute patients, (2) subacute patients and chronic patients, and (3) acute patients and chronic patients. All 3 symptom duration groups were combined for linear regression analyses, which were used to determine whether any of the intervention combinations or patient variables was predictive of functional improvement. A univariate analysis was conducted first to determine the relation between functional improvement and the independent variables. All independent variables that were found to have a significant correlation with the dependent variable were entered into a stepwise regression analysis. Decisions to retain or delete variables at each step were based on their level of association with the dependent variable, their contribution to the model and comparison of the partial F statistic. All analyses were performed using SAS statistical software. a RESULTS Mean functional outcome scores and the mean functional improvement from pretherapy to posttherapy are identified in table 4. No significant differences in initial function (P.20) or functional outcome scores (P.31) existed between the groups. Persons in the chronic group had significantly less functional improvement than persons in the acute group (P.05). Significant differences were found within each of the groups between pretreatment and posttreatment function scores. The average functional improvement score from pretreatment to posttreatment was 10.7 for the chronic group, 15.6 for the subacute group, and 19.3 for the acute group. The median percentage improvement scores for pain and perceived improvement are shown in table 5. The decrease in pain from pretreatment to posttreatment was significant for all groups (P.05). There was no significant difference in percentage decrease in pain when comparing the acute, subacute, and chronic groups. However, the median percentage decrease in pain was 72.5% for the acute group, whereas the median scores for the subacute and chronic groups were only 60% and 62%, respectively. The median percentage improvement score for perceived recovery was significantly lower for the chronic group than for the acute group (P.05). Linear regression analyses were used to identify variables with an independent association with the functional improvement score. An ANOVA of the regression line confirmed that the relation between the dependent and all independent vari- Table 5: Median Improvement Scores Outcome Acute Subacute Chronic P Decrease in pain* (%) NS Interquartile range Perceived improvement (%) Interquartile range Abbreviation: NS, not significant. *Percentage decrease in pain (initial pain final pain)/initial pain. Percentage improvement perceived improvement 10. Pairwise comparison reveals difference between acute and chronic groups

4 752 PHYSICAL THERAPY FOR PATIENTS WITH LOW BACK PAIN, Badke Table 6: Regression Model Explaining 55.5% of Variance in the Functional Improvement Score Among All LBP Patients Independent Variable Functional Improvement Range (1 100) b t P Age Initial function Symptom duration Flexibility, strengthening, and mobilization/manipulation ables is unlikely to have occurred by chance (F , P.001). A model with age (P.001), symptom duration (P.002), and inclusion of strengthening, flexibility, and mobilization/manipulation treatments (P.001) fit the data well and explained 55.5% of the variance (table 6). DISCUSSION The purposes of this study included assessing the impact of symptom duration on functional outcomes in patients with LBP following PT care and determine which variables were associated with enhanced function. Analysis of data showed that a combined intervention approach was effective in reducing patient pain and increasing function. The interventions selected by therapists associated with our study were not entirely consistent with results of previously published studies. Strengthening and flexibility exercises were the most frequently noted intervention choices in our study, similar to results reported by Jette and Jette 8 and Jette and Delitto, 10 but mobilization/manipulation techniques were utilized more frequently by our therapists. These techniques were utilized in 38% to 52% of the episodes of care (see table 2) depending on the patient acuity level, compared with a high of 39% 8 and 27% 10 previously reported. Some possible explanations for these discrepancies include: (1) differences in patient population or clinical environment, (2) unequal training or skill level of the therapy providers, or (3) increased research knowledge and use of evidence-based practice. Nonetheless, these choices are compliant with studies supporting its use for patients with LBP 18,19 and the inclusion of this intervention in the Guide to Physical Therapist Practice. 9 Another area of discrepancy is the marked difference in utilization of heat modalities. In our study, heat was used very infrequently regardless of patient acuity (see table 2), while it was utilized for 81% and 83% to 88% of patients in the Jette and Delitto 10 and Jette and Jette 8 studies, respectively. The trend of adopting a more active intervention approach (eg, exercises), less reliance on passive modalities (eg, heat), and utilizing manual therapy techniques to quicken recovery is consistent with the recommended guidelines for treating patients with acute LBP. 20 The change in degree of disability following PT intervention was associated with degree of patient acuity for most measures. For example, the median score for patient-perceived improvement and the functional improvement score from initial visit to discharge was significantly less for the chronic group than for the acute group. These results are consistent with those of Ross 13 who found that patients with symptom duration of less than 1 month had the greatest decrease in disability and those with chronic duration ( 6mo) the smallest decrease. One possible explanation for this trend is patients with longer symptom duration may have an increased possibility of developing associated psychosocial factors which could result in lower function and perceived recovery. Patients with specific psychosocial elements have been shown to have poor recovery from chronic neck and LBP at 1 year. 21,22 Our results do differ when compared with another study using CareConnections Outcomes System data, which indicated no clinically significant differences between acute, subacute, and chronic groups for patients with LBP. 23 Direct comparison of results, though, is difficult due to the varying time frames marking the acute, subacute, and chronic symptom duration periods. Based on stages of tissue healing postinjury, Self et al 23 used 0 to 7 days postinjury as the parameters for the acute group, 8 to 14 days for subacute, and 15 to 42 days for chronic. Considering that not all of our patients suffered an acute injury, we made the decision to use a different previously established timeframe. Last, the greatest amount of change in bodily pain, often the primary patient goal, appeared to occur in the acute phase, even though this was not statistically significant. Reduction of pain has been reported as a treatment goal for 90% of the patients treated by physical therapists for LBP. 24 Of importance to clinicians is whether factors can be identified that are predictive of variability in pain and disability improvement. The importance of early intervention and rapid reduction of disability is described in studies demonstrating that in patients with LBP experiencing disability for 4 weeks or more are at higher risk for chronic disability and work restrictions Very little is known about factors that predict treatment outcome for patients with LBP. The regression analyses in this study indicated that age, symptom duration, and the inclusion of strengthening and flexibility exercises and mobilization/manipulation were the most important determinants of functional outcome score as an indication of disability. Of particular relevance, the combination of treatments that included mobilization/manipulation was the most consistent treatment predictor of better outcome. This finding differs from Jette and Jette s report 8 that inclusion of endurance exercise was most consistently associated with better outcomes, but it is consistent with recent studies that reported improved outcomes for patients with LBP and other conditions receiving mobilization/manipulation in conjunction with exercise therapy versus those patients who did not receive the manual therapy interventions. 19,29,30 Our results support the importance of including mobilization/manipulation techniques into patient plans of care for those with LBP. The prevalence of depression in our three patient groups ranged from 18% to 26%. Of concern is that most patients with major depression go unrecognized or are inappropriately managed Considering this, clinicians should be screening for depression in patients with LBP. A 2-question screening instrument has been advocated for clinical use. 34,35 Whooley et al 34 found that the questions: (1) During the past month, have you often been bothered by feeling down, depressed, or hopeless? and (2) During the past month have you often been bothered by little interest or pleasure in doing things? showed a 96% sensitivity (95% confidence interval [CI], 90% 99%) with a negative likelihood ratio of.07, a negative predictive value of 98%, and a specificity of 57% (95% CI, 53% 62%), with a positive likelihood ratio of 2.2 and a positive predictive value of 33%. The recommendation was that a patient yes response to either or both of the questions would warrant further screening, including inquiry of weight change, sleep disturbance, psychomotor problems, lack of energy, excessive guilt, poor concentration, and recurrent suicidal ideation. A cluster of 5 or more of the findings (including either or both of the initial 2 screening questions) present for at least 2 weeks causing significant distress in social, occupational, or other important areas of functioning would warrant a patient referral for further psychologic screening. 36

5 PHYSICAL THERAPY FOR PATIENTS WITH LOW BACK PAIN, Badke 753 APPENDIX 1: CARE CONNECTIONS OUTCOMES INSTRUMENT

6 754 PHYSICAL THERAPY FOR PATIENTS WITH LOW BACK PAIN, Badke

7 PHYSICAL THERAPY FOR PATIENTS WITH LOW BACK PAIN, Badke 755 Regarding the number of therapy visits, the acute and subacute groups averaged approximately 5 to 7 visits over 7 to 9 weeks, whereas the chronic group averaged 8 visits over 11 weeks. This study s finding concerning visit utilization appears to be consistent with a report by Amato et al, 37 who found that patients beginning therapy within the acute phase averaged fewer visits than all other groups. Study Limitations This study was a retrospective clinical report that precludes any conclusions about the effectiveness of the provided PT interventions. The study findings are based on analysis of a clinical database that is used to monitor patient outcomes and for quality improvement. Several possible biases related to the use of clinical databases and issues in using them for predicting outcomes have been clearly described by Pryor and Lee 38 and Jette and Jette. 8 These include (1) database lacked information concerning specific impairments such as flexibility and muscle strength, (2) use of data to answer questions not determined a priori, (3) missing observations, (4) selection and referral bias, and (5) large numbers of variables may threaten the validity of the predictions. Despite these limitations, our results provide valuable information concerning the relation of choice of PT interventions to functional outcomes and the optimal timing of therapy services. The results can also be used to help establish a patient prognosis, generate research hypotheses and for designing future research trials. CONCLUSIONS The aims of this clinical report were (1) to assess the impact of symptom duration on functional outcomes following rehabilitation for patients with LBP, (2) to determine the patient s perception of recovery following discharge from therapy, and (3) to determine what variables were associated with improved function. Regardless of acuity, improvements in function and pain occur over the course of PT care, especially when strengthening, flexibility exercises, and mobilization/manipulation are included in the treatment plan. Patients seen in the chronic phase had lower functional improvement and perceived improvement scores than the acute group. References 1. Jarvik JG, Deyo RA. Diagnostic evaluation of low back pain with emphasis on imaging. Ann Intern Med 2002;137: Woodwell DA, Cherry DK. National Ambulatory Medical Care Survey: 2002 summary. Adv Data 2004;(346): Stewart WF, Ricci JA, Chee E, Morganstein D, Lipton R. Lost productive time and cost due to common pain conditions in the US workforce. JAMA 2003;290: Luo X, Pietrobon R, Sun SX, Liu GG, Hey L. Estimates and patterns of direct health care expenditures among individuals with back pain in the United States. Spine 2004;29: Jette AM, Davis KD. A comparison of hospital-based and private outpatient physical therapy practices. Phys Ther 1991; 71: Di Fabio R, Boissonnault W. Physical therapy and health-related outcomes for patients with common orthopaedic diagnoses. J Orthop Sports Phys Ther 1998;27: Boissonnault WG. Prevalence of comorbid conditions, surgeries, and medication use in a physical therapy outpatient population: a multicentered study. J Orthop Sports Phys Ther 1999; 29: Jette DU, Jette AM. Physical therapy and health outcomes in patients with spinal impairments. Phys Ther 1996;76: American Physical Therapy Association. Guide to Physical Therapist Practice. 2nd edition. Phys Ther 2001;81: Jette AM, Delitto A. Physical therapy treatment choices for musculoskeletal impairments. Phys Ther 1997;77: Di Fabio RP, Mackey G, Holte JB. Disability and functional status in patients with low back pain receiving worker s compensation: a descriptive study with implications for the efficacy of physical therapy. Phys Ther 1995;75: Greenough CG, Fraser RD. The effects of compensation on recovery from low back injury. Spine 1989;14: Ross MD. Physical therapy and changes in disability for patients with low back pain. Mil Med 2002;167: International classification of diseases 9th revision coding manual for physicians. Vols 1, 2. West Valley City: Ingenix; Schunk C, Rutt R. TAOS functional index: orthopaedic rehabilitation outcomes tool. J Rehabil Outcomes Meas 1998;2: Williamson A, Hoggart B. Pain: a review of three commonly used pain rating scales. J Clin Nurs 2005;14: Gallagher EJ, Bijur PE, Latimer C, Silver W. Reliability and validity of a visual analog scale for acute abdominal pain in the ED. Am J Emerg Med 2002;20: Flynn T, Fritz J, Whitman J, et al. A clinical prediction rule for classifying patients with low back pain who demonstrate shortterm improvement with spinal manipulation. Spine 2002;27: Childs JD, Fritz JM, Flynn TW, et al. A clinical prediction rule to identify patients with low back pain most likely to benefit from spinal manipulation: a validation study. Ann Intern Med 2004; 141: Bigos S, Boyer O, Brean G, Brown K, Deyo R, Kido D. Acute lower back problems in adults. Rockville: Agency for Health Care Policy and Research; AHCPR Publication No Riipinen M, Niemisto L, Lindgren KA, Hurri H. Psychosocial differences as predictors for recovery from chronic low back pain following manipulation, stabilizing exercises and physician consultation or physician consultation alone. J Rehabil Med 2005;37: Radanov P, Sturzenegger M, Di Stefano G. Prediction of recovery from dislocation of the cervical vertebrae (whiplash injury of the cervical vertebrae) with initial assessment of psychosocial variables. Orthopade 1994;23: Self DD, Barnes B, Larson B, Roskammer Saleen T, Hager G, El-Din D. Influence of patient acuity on physical therapy outcomes and utilization. Orthop Phys Ther Clin North Am 2000; 9(11): Jette AM, Smith K, Haley SM, Davis KD. Physical therapy episodes of care for patients with low back pain. Phys Ther 1994:74: Fritz JM, George SZ. Identifying psychosocial variables in patients with acute work-related low back pain: the importance of fear-avoidance beliefs. Phys Ther 2002;82: Frank JW, Brooker AS, DeMaio SE, et al. Disability resulting from occupational low back pain. Part II: What do we know about secondary prevention? A review of the scientific evidence on prevention after disability begins. Spine 1996;21: Hashemi L, Webster BS, Clancy EA. Trends in disability duration and cost of worker s compensation low back pain claims. J Occup Environ Med 1998;40: Hiebert R, Skovron ML, Nordin M, Crane M. Work restrictions and outcome of nonspecific low back pain. Spine 2003;28:

8 756 PHYSICAL THERAPY FOR PATIENTS WITH LOW BACK PAIN, Badke 29. Deyle GD, Henderson NE, Matekel RL, Ryder MG, Garber MB, Allison SC. Effectiveness of manual physical therapy and exercise in osteoarthritis of the knee. A randomized, controlled trial. Ann Intern Med 2000;132: Hoeksma HL, Dekker J, Ronday HK, et al. Comparison of manual therapy and exercise therapy in osteoarthritis of the hip: a randomized clinical trial. Arthritis Rheum 2004;51: Katon W, von Korff M, Lin E, Bush T, Ormel J. Adequacy and duration of antidepressant treatment in primary care. Med Care 1992;30: Simon GE, von Korff M, Wagner EH, Barlow W. Patterns of antidepressant use in community practice. Gen Hosp Psychiatry 1993;15: Hirschfield RM, Keller MB, Panico S, et al. The National Depressive and Manic-Depressive Association consensus statement on the undertreatment of depression. JAMA 1997;277: Whooley MA, Avins AL, Miranda J, Browner WS. Case-finding instruments for depression. Two questions are as good as many. J Gen Intern Med 1997;12: Haggman S, Maher CG, Refshauge KM. Screening for symptoms of depression by physical therapists managing low back pain. Phys Ther 2004;84: Whooley MA, Simon GE. Managing depression in medical outpatients. N Engl J Med 2000;343: Amato AL, Dobrzykowski EZ, Nance T. The effect of timely onset of rehabilitation on outcomes in outpatient orthopedic practice: a preliminary report. J Rehabil Outcomes Meas 1997;1: Pryor DB, Lee KL. Methods for the analysis and assessment of clinical databases: the clinician s perspective. Stat Med 1991;10: Supplier a. Release 6.12; SAS Institute Inc, 100 SAS Campus Dr, Cary, NC