Comparison of Use of Short Form-36 Domain Scores and Patient Responses for Derivation of Preference-Based SF6D Index to Calculate Quality-Adjusted Life Years in Patients with Intermittent Claudication.

BACKGROUND: The short form 36 (SF36) questionnaire is used for assessment of generic quality of life. Responses to the individual question in SF36 are also used for calculation of the SF6D index score. This score is used for calculation of quality adjusted-life years (QALYs) in economical analyses. As the individual patient questionnaires are not always available for performing systematic reviews and meta-analyses, a new formula has been developed for derivation of SF6D index score from the reported SF36-domain scores. This study aimed to evaluate the validity of this formula for use in patients with intermittent claudication. METHODS: A retrospective review of a prospectively collected database of a randomized controlled trial was performed. A total of 178 patients were recruited. Clinical indicators of ischemia were recorded. All patients completed SF36 questionnaires. Response and domain-based SF6D scores (R-SF6D and D-SF6D) and QALYs were calculated. Correlation and agreement analysis were performed. RESULTS: Response rate was 88% (n = 781) over a 1-year follow-up period. Domain-based SF6D score (mean, 0.684; standard deviation [SD] 0.110) was significantly higher (paired t-test, P = 0.001) than the response-based score (mean, 0.627; SD, 0.110) with a mean difference of 0.056 (95% confidence interval, 0.053-0.060). Mean QALY calculated using D-SF6D score (0.503; SD, 0.116) was also significantly higher than the QALY calculated from the R-SF6D score (0.467; SD, 0.121). Bland-Altman comparison showed strong agreement (limit of agreement -0.167 to 0.054) between the 2 methods with equal variances (Pitman's test, P = 0.629). D-SF6D scores showed stronger correlation with clinical indicators of ischemia (r = 0.246-0.602) compared with that of R-SF6D scores (r = 0.233-0.549). CONCLUSIONS: Domain-based estimation of SF6D score is a valid and reliable method with strong agreement to the gold standard response-based scores in claudicants. However, adjustments may be required in studies using a mixture of D-SF6D and R-SF6D scores for QALY calculation.

A randomized placebo controlled trial of the effect of preoperative statin use on matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in areas of low and peak wall stress in patients undergoing elective open repair of abdominal aortic aneurysm.

BACKGROUND: A double-blind, randomized controlled trial was carried out to study the effects of statins on matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) in areas of peak and low abdominal aortic aneurysm (AAA) wall stress. METHODS: A total of 40 patients undergoing elective open AAA repair were randomized to receive either atorvastatin 80 mg (n = 20) or placebo (n = 20) for 4 weeks preoperatively. Finite element analysis was used to determine AAA wall stress distribution. Full thickness aortic samples were obtained at surgery from areas of low and peak wall stress, snap-frozen, and stored at -80°C for subsequent MMP-2, -8, and -9 and TIMP-1 and -2 analyses. Statistical analysis was performed using SPSS 16.0 (SPSS Inc, Chicago, IL). RESULTS: Both groups were well matched (p > 0.05) regarding age, gender, comorbidities, and duration of hospital stay. There were no statistically significant differences in levels of MMPs and TIMPs between the statin and placebo group and between areas of low and peak AAA wall stress. CONCLUSION: The short-term use of statins is not associated in reducing levels of MMP 2, 8, and 9 and TIMP-1 and -2 in areas of low and peak wall stress in patients with AAA.