Jason W. Busse

The Philosophy of Evidence-Based Medicine

This chapter is drawn largely from a chapter in another book, the Users’ Guide to the Medical Literature (1). As the first reference to evidence-based medicine (EBM) in the published literature makes evident, EBM is about solving clinical problems (2). Historically, clinicians found solutions to problems in manuals, textbooks, or in counsel from senior colleagues. Time and experience were seen as sufficient to impart clinical wisdom. As it turned out, however, this paradigm of education and practice resulted in wide practice variations across institutions. At the same time, although important clinical research was available, few clinicians had the skillset required to critically evaluate that literature and decide on the best way to incorporate findings into clinical practice.

Delayed presentation of cauda equina syndrome secondary to lumbar disc herniation: functional outcomes and health-related quality of life.

OBJECTIVE Cauda equina syndrome (CES) is a feared complication of lumbar disc herniation. It is generally accepted that CES requires decompression within 6 hours of symptom onset, but this time goal is rarely met, and the relative benefit of delayed decompression on functional status and quality of life (QOL) remains unknown. The study objective was to describe the functional status and quality of life outcomes for patients who undergo delayed surgical decompression for CES. METHODS Patients with CES who underwent decompression of a herniated lumbar disc during a 10-year period were assessed at hospital discharge and at least 4 months after the procedure. Evaluation of functional outcomes was based on a previously validated scale and QOL outcomes on the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) questionnaire. RESULTS During the study period, 1100 patients with herniated discs were identified, and 14 underwent surgical decompression for CES. All 14 had had symptoms for more than 38 hours before surgery. Ten patients were available for long-term follow-up. There was a strong correlation between long CES symptom duration and poor functional outcome: of 8 patients with symptoms for less than 10 days before decompression (range, 1.6-7.5 d), all had good functional outcomes. The 2 patients with more prolonged symptoms (10.6 and 14.2 d) had poor outcomes. SF-36 scores demonstrated declines in physical roles (p = 0.03), social function (p = 0.03) and increased pain (p = 0.003) compared with population norms. Correlation between SF-36 domain scores and CES symptom duration failed to achieve statistical significance, perhaps because of small sample size. CONCLUSIONS Patients who undergo delayed decompression for CES have increased pain and impaired social and physical function. Longer delays correlate with worse functional outcomes. Beyond 24 hours, decompression delay may be associated with a poorer quality of life but, because of the rarity of CES, the sample size in this study was too small to provide definitive conclusions. Since no patients underwent surgery within 38.4 hours of symptoms, it is not possible to comment on the importance of emergent decompression in early presenters.

Factors associated with the duration of disability benefits claims among Canadian workers: a retrospective cohort study

BACKGROUND Disability insurance protects workers from total loss of income in case of a disabling injury or illness by providing wage-replacement benefits. To better inform early identification of claims at risk of prolonged recovery, we explored predictors of the duration of disability benefits claims. METHODS We conducted a retrospective cohort study using claims data provided by SSQ Life Insurance Company Inc., a private Canadian disability insurer. We examined all claims SSQ approved for short- and long-term disability benefits from Jan. 1, 2007, to Mar. 31, 2014, and evaluated the association between 9 variables and duration of short- and long-term disability benefits using Cox proportional hazards regression analyses. RESULTS For both short- (n = 70 776) and long-term disability (n = 22 205) claims, and across all disorders, older age, female sex, heavy job demands, presence of comorbidity, attending an independent medical evaluation, receipt of rehabilitation therapy and longer time to claim approval were associated with longer claim duration. Higher predisability salary was associated with longer short-term disability claim duration. Quebec residency was associated with longer short-term disability claim duration among workers with psychological disorders, but shorter short-term disability claim duration among those with musculoskeletal complaints and other illnesses. For long-term disability claims, however, residing in Quebec was associated with shorter claim duration, although the size of the association differed across clinical conditions. INTERPRETATION The factors we found to be associated with the duration of short- and long-term disability claims may be helpful to identify claims at risk of prolonged recovery. Our study has limitations, however, and well-designed prospective studies are needed to confirm our findings and identify other promising predictors.