Development of a mapping function ("crosswalk") for the conversion of scores between the Oswestry Disability Index (ODI) and the Core Outcome Measures Index (COMI).

INTRODUCTION: The Oswestry Disability Index (ODI) and the Core Outcome Measures Index (COMI) are two commonly used self-rating outcome instruments in patients with lumbar spinal disorders. No formal crosswalk between them exists that would otherwise allow the scores of one to be interpreted in terms of the other. We aimed to create such a mapping function. METHODS: We performed a secondary analysis of ODI and COMI data previously collected from 3324 patients (57 ± 17y; 60.3% female) at baseline and 1y after surgical or conservative treatment. Correlations between scores and Cohen's kappa for agreement (κ) regarding achievement of the minimal clinically important change (MCIC) score on each instrument (ODI, 12.8 points; COMI, 2.2 points) were calculated, and regression models were built. The latter were tested for accuracy in an independent set of registry data from 634 patients (60 ± 15y; 56.8% female). RESULTS: All pairs of measures were significantly positively correlated (baseline, 0.73; 1y follow-up (FU), 0.84; change-scores, 0.73). MCIC for COMI was achieved in 53.9% patients and for ODI, in 52.4%, with 78% agreement on an individual basis (κ = 0.56). Standard errors for the regression slopes and intercepts were low, indicating excellent prediction at the group level, but root mean square residuals (reflecting individual error) were relatively high. ODI was predicted as COMI × 7.13-4.20 (at baseline), COMI × 6.34 + 2.67 (at FU) and COMI × 5.18 + 1.92 (for change-score); COMI was predicted as ODI × 0.075 + 3.64 (baseline), ODI × 0.113 + 0.96 (FU), and ODI × 0.102 + 1.10 (change-score). ICCs were 0.63-0.87 for derived versus actual scores. CONCLUSION: Predictions at the group level were very good and met standards justifying the pooling of data. However, we caution against using individual values for treatment decisions, e.g. attempting to monitor patients over time, first with one instrument and then with the other, due to the lower statistical precision at the individual level. The ability to convert scores via the developed mapping function should open up more centres/registries for collaboration and facilitate the combining of data in meta-analyses.

Use and outcomes of venous thromboembolism prophylaxis after spinal fusion surgery.

BACKGROUND: The number of spinal fusion operations in the USA is rapidly rising, but little is known about optimal venous thromboembolism prophylaxis after spinal surgery. OBJECTIVES: To examine the use of and outcomes associated with venous thromboembolism prophylaxis after spinal fusion surgery in a cohort of 244 US hospitals. PATIENTS/METHODS: We identified all patients with a principal procedure code for spinal fusion surgery in hospitals participating in the Premier Perspective database from 2003 to 2005, and searched for receipt of pharmacologic prophylaxis (subcutaneous unfractionated heparin, low molecular weight heparin, or fondaparinux) and/or mechanical prophylaxis (compression devices and elastic stockings) within the first 7 days after surgery. We also searched for discharge diagnosis codes for venous thromboembolism and postoperative hemorrhage during the index hospitalization and within 30 days after surgery. RESULTS: Among 80,183 spinal fusions performed during the time period, cervical fusions were the most common (49.0%), followed by lumbar fusions (47.8%). Thromboembolism prophylaxis was administered to 60.6% of patients within the first week postoperatively, with the most frequent form being mechanical prophylaxis alone (47.6%). Of the 244 hospitals, 26.2% provided prophylaxis to ≥ 90% of their patients undergoing spinal fusion; however, 33.2% provided prophylaxis to fewer than 50% of their patients. The rate of diagnosed venous thromboembolism within 30 days after surgery was 0.45%, and the rate of postoperative hemorrhage was 1.1%. CONCLUSIONS: Substantial variation exists in the use of thromboembolism prophylaxis after spinal fusion surgery in the USA. Nevertheless, overall rates of diagnosed thromboembolism after spinal fusion appear to be low.

Lumbar discectomy outcomes vary by herniation level in the Spine Patient Outcomes Research Trial.

BACKGROUND: The Spine Patient Outcomes Research Trial showed an overall advantage for operative compared with nonoperative treatment of lumbar disc herniations. Because a recent randomized trial showed no benefit for operative treatment of a disc at the lumbosacral junction (L5-S1), we reviewed subgroups within the Spine Patient Outcomes Research Trial to assess the effect of herniation level on outcomes of operative and nonoperative care. METHODS: The combined randomized and observation cohorts of the Spine Patient Outcomes Research Trial were analyzed by actual treatment received stratified by level of disc herniation. Overall, 646 L5-S1 herniations, 456 L4-L5 herniations, and eighty-eight upper lumbar (L2-L3 or L3-L4) herniations were evaluated. Primary outcome measures were the Short Form-36 bodily pain and physical functioning scales and the modified Oswestry Disability Index assessed at six weeks, three months, six months, one year, and two years. Treatment effects (the improvement in the operative group minus the improvement in the nonoperative group) were estimated with use of longitudinal regression models, adjusting for important covariates. RESULTS: At two years, patients with upper lumbar herniations (L2-L3 or L3-L4) showed a significantly greater treatment effect from surgery than did patients with L5-S1 herniations for all outcome measures: 24.6 and 7.1, respectively, for bodily pain (p = 0.002); 23.4 and 9.9 for Short Form-36 physical functioning (p = 0.014); and -19 and -10.3 for Oswestry Disability Index (p = 0.033). There was a trend toward greater treatment effect for surgery at L4-L5 compared with L5-S1, but this was significant only for the Short Form-36 physical functioning subscale (p = 0.006). Differences in treatment effects between the upper lumbar levels and L4-L5 were significant for Short Form-36 bodily pain only (p = 0.018). CONCLUSIONS: The advantage of operative compared with nonoperative treatment varied by herniation level, with the smallest treatment effects at L5-S1, intermediate effects at L4-L5, and the largest effects at L2-L3 and L3-L4. This difference in effect was mainly a result of less improvement in patients with upper lumbar herniations after nonoperative treatment.

Shared decision-making and the orthopaedic workforce.

Studies of physician workforce need a standard of an appropriately sized workforce to compare projections. Although many studies use average rates of healthcare use as a standard, regional benchmarks provide a pragmatic alternative approach to estimating a reasonably sized physician workforce and avoid many of the problems of needs- and demand-based planning. Wide geographic variations in the rates of many procedures, unexplained by differences in population characteristics, suggest that supply-induced demand or physician practice style or both may be the major determinates of the rates for these procedures. In the current study, the authors explore some of these differences in orthopaedic procedure rates and their implications for workforce planning. For example, the rates of hip fracture are fairly uniform across geographic regions, whereas the rates of spine surgery vary sixfold and the rates of spinal fusion vary 10-fold. Shared decision-making is the process of giving patients informed choices about their treatment options based on current best evidence. Careful studies of treatment effectiveness and shared decision-making hold the promise of allowing patients' preferences and values to determine the right rate of healthcare use. These rates could allow workforce projections to be compared with optimal benchmarks for future planning.

Teaching evidence-based medicine: caveats and challenges.

Evidence-based medicine (EBM) is an important new paradigm of the medical profession. While the quantitative approach of EBM has its place, clinical medicine must take into account many subtleties that EBM fails to consider. In this article, the authors describe three caveats to this quantitative approach: (1) the detection of "maybe disease" (physiologic, anatomic, or histologic abnormalities that may not ever be overtly expressed in the patient's lifetime) inflates apparent diagnostic test performance; (2) probability revision is valuable primarily as an exercise to gain qualitative insights; and (3) patients are likely to be interested more than just central tendencies in making treatment decisions. They then consider some challenging questions facing clinician-educators: how do they prepare students for situations where there is an absence of rigorous evidence? Should they teach students that the burden of proof lies in demonstrating efficacy or in demonstrating ineffectiveness? And what should they tell students about when to seek evidence to aid diagnostic and treatment decisions?

Diagnostic testing following fecal occult blood screening in the elderly.

BACKGROUND: Screening with a fecal occult blood test (FOBT) has been shown to reduce colorectal cancer mortality in controlled trials. Recently, Medicare approved payment for FOBT screening. We evaluated the pattern of diagnostic testing following the initial FOBT in elderly Medicare beneficiaries. Such follow-up testing would in the long run influence both the cost and the benefit of widespread use of FOBT. METHODS: Using Medicare's National Claims History System, we identified 24 246 Americans 65 years old or older who received FOBT at physician visits between January 1 and April 30, 1995. Prior to FOBT, these people had no evidence of any conditions for which FOBT might be used diagnostically. We examined relevant diagnostic testing in this cohort during the subsequent 8 months and determined what proportion of those received an evaluation recommended by the American College of Physicians. RESULTS: For every 1000 Medicare beneficiaries who received FOBT, 93 (95% confidence interval = 89-96 per 1000) had positive findings and relevant testing in the subsequent 8 months. Of these, 34% had the recommended evaluation of either colonoscopy or flexible sigmoidoscopy with an air-contrast barium enema. Another 34% received a partial colonic evaluation with either flexible sigmoidoscopy or a barium enema. The remaining 32% received other gastrointestinal (GI) testing without evaluation of the colonic lumen: computed tomography or magnetic resonance imaging of the abdomen (15%), upper GI series (10%), carcinoembryonic antigen (7%), and upper endoscopy (2%). Restricting the analysis to testing performed within 2 months of the initial FOBT yielded similar results. CONCLUSION: Following FOBT, many Medicare beneficiaries get further diagnostic testing, but only a small proportion receives the recommended evaluation. With this pattern of practice, population screening is likely to be more costly and less effective than estimated from controlled trials.

Hospitalist staffing requirements.

CONTEXT: The use of hospitalists--physicians who spend a substantial portion of their time providing in-hospital care to the patients of primary care physicians--has been proposed as a way to decrease costs and increase the quality of inpatient care. COUNT: Number of full-time hospitalists. CALCULATIONS: Average daily census = annual admissions x length of stay divided by 365. Number of hospitalists = (average daily census divided by patients per hospitalist) + 1 extra hospitalist for night coverage. DATA SOURCES: The average number of patients per hospitalist was obtained from a National Association of Inpatient Physicians membership survey. A low estimate of 10 patients per hospitalist was used to account for the extra manpower needed for coverage during vacations and other time off. RESULTS: A hospital with 3000 admissions per year and an average length of stay of 5 days would have an average daily census of 41 patients and would need 5 full-time hospitalists. Hospitals with a lower patient volume would need fewer hospitalists and would probably need to find persons other than hospitalists to cover some nights and weekends. CONCLUSIONS: Simple calculations based on hospital admissions and length of stay can estimate the number of hospitalists required for adequate staffing. Requirements will vary with the hospitalists' workload; the patient case complexity; and the duties other than inpatient care that are required of hospitalists, such as consultations, skilled nursing facility coverage, quality improvement work, teaching, and research.

The potential size of the hospitalist workforce in the United States.

PURPOSE: In the United States, there are currently 1,000 to 2,000 physicians who specialize in inpatient hospital care. The number of such hospitatists appears to be growing rapidly, but the ultimate size of the hospitalist workforce is not known. METHODS: We obtained workload data from 365 practicing hospitalists who completed a survey by the National Association of Inpatient Physicians. We then estimated the number of potential hospitalists, based on published national hospital census data. We assumed that hospitalists would care for all medical inpatients, but only at hospitals large enough to require > or = 3 hospitalists. We also made estimates based on the primary care physician referral base and international benchmarks. We estimated hospitalists' primary care referral base from telephone interviews with key informants. Official sources in England and Germany provided international workforce data. RESULTS: Hospitalists reported an average workload of 13 inpatients. To cover all adult medical inpatients in the United States, we estimate a potential workforce of 19,000 hospitalists. Sensitivity analysis yielded 10,000 to 30,000 hospitalists. Our alternative models yielded estimates within this same range. CONCLUSIONS: The future hospitalist workforce is potentially quite large. This finding highlights the need to evaluate the economic and clinical outcomes of hospitalist systems.

Principles of medical decision making.

The consequences of medical decisions are inherently uncertain at the decisive moment. Using clinical examples related to the diagnosis and management of low back pain, the authors review some principles that can help physicians deal with this uncertainty. This article addresses the following: the use of probability as a useful representation of uncertainty, the use of Bayes' theorem to update probability estimates when new information is obtained, the measurement of a diagnostic test's accuracy, the use of the threshold model for choosing a diagnostic test, the principles of expected-value decision making, the use of utility assessment as a way of attaching value to outcomes, and the use of quality-adjusted life years as a measure of value. These principles can aid physicians in approaching complex and uncertain decisions with their patients. As the use of computers becomes more integrated into the process of care, the opportunity exists to move formal decision models from the policy level to the patient care level.