Establishing minimal clinically important difference for the UCLA and ASES scores after rotator cuff repair.

BACKGROUND/HYPOTHESIS: Minimal clinically important difference (MCID) is a vital tool in the analysis of clinical results. It allows the determination of clinical relevance of statistical data. Our hypothesis was that specific differences between preoperative and postoperative scores would be able to accurately predict patient perception of improvement and satisfaction as reflected by anchor and distribution-based questions. METHODS: Retrospective cohort with patients that underwent rotator cuff repair. We evaluated the University of California at Los Angeles Shoulder Rating Scale (UCLA) and the American Shoulder and Elbow Surgeons Assessment Form (ASES) before and 12-months after surgery. Anchor-based, distribution-based and minimum detectable change (MDC) approaches were utilized. RESULTS: We evaluated 289 shoulders. The MCID for the UCLA scale was 4.5 points using the anchor method, 2.5 by the distribution method and 3.6 by MDC. Patients with a baseline score>20 presented a lower MCID (1.5, 1.1 and 1.7, respectively). For the ASES score, the MCID was 6.1 by the anchor method, 10.5 based on the distribution method and 26.3 by MDC. In the group of patients above the 60 point cutoff, the obtained values were 2.4, 4.9 and 13.6, respectively. CONCLUSION: The mean MCID value for the UCLA shoulder score is 3.5 points, ranging from 2.5 points (distribution method) to 4.5 points (anchor method). The mean MCID value for the ASES score was 15.2 points, ranging from 6.1 (anchor method) to 26.3 (MDC). Patients groups presenting with higher preoperative scores showed lower MCID values. This fact needs to be considered in postoperative comparisons between treatment groups. LEVEL OF EVIDENCE: Basic Science Study, Validation of Outcomes Instruments/Classification Systems.

Vancomycin minimum inhibitory concentrations and lethality in Staphylococcus aureus bacteremia.

BACKGROUND: After the dissemination of penicillin and oxacillin resistance in Staphylococcus aureus, vancomycin-intermediate and vancomycin resistant isolates have been reported. Even between isolates with minimum inhibitory concentrations (MICs) within the susceptible range, some authors have demonstrated that higher MICs correlate with higher lethality. METHODS: To test this hypothesis in our setting, we compared vancomycin MICs evaluated by two methods and clinical outcomes in hospitalized patients with S. aureus bacteremia. RESULTS: We compared lethality in patients infected with isolates that had MICs under or over 2 mg/L. Among patients infected with isolates that had microdilution MICs <2 mg/L, the lethality was 25%; among patients infected with strains that had microdilution MICs ≥2 mg/L, 33% died. Among patients infected with isolates that had Etest MICs <2 mg/L, 23% died; in comparison, patients infected with strains that had Etest MICs ≥2 mg/L had a lethality of 44%. CONCLUSION: Our results showed a slight tendency of higher lethality when higher MICs were present. However, this difference did not reach statistical significance, possibly due to the relatively small number of patients included in the study. Future prospective studies are needed to further evaluate this correlation and to help clinicians guide antimicrobial therapy.