Measuring the health status burden in hemodialysis patients using the SF-36® health survey.

PURPOSE: The SF-36, a generic measure of 8 domains of health-related quality of life (HRQOL), has been widely used to examine HRQOL of end-stage renal disease (ESRD) patients undergoing hemodialysis (HD). The current study synthesizes existing literature to examine which SF-36 domains capture the largest burden in this patient population. METHODS: A literature search of published studies that presented descriptive statistics for baseline SF-36 scale scores from HD patients was conducted. Disease burden was estimated by comparing HD patients' SF-36 scores to those from either a control group or a general population normative sample taken from the same country. For each study, Cohen d effect sizes for between-sample differences were calculated for each scale. RESULTS: Twenty-six articles that matched set criteria were identified. Estimation of differences between HD patients and comparison groups showed that the SF-36 physical functioning scale yielded the largest weighted mean effect size across studies (d = 1.46), followed by the general health (d = 1.29) and role physical (d = 1.21) scales. CONCLUSIONS: Among the eight domains of the SF-36, physical functioning, general health, and role physical scales best captured disease burden for HD patients. The disease burden negatively impacts physical HRQOL more strongly than mental HRQOL.

The minimally important difference of the Asthma Control Test.

BACKGROUND: The Asthma Control Test (ACT) has been well validated, but a minimally important difference (MID) has not been established. OBJECTIVE: We sought to identify an MID for the ACT. METHODS: Data come from 4 independent samples of adult asthmatic patients. Distributional methods for determining the MID included 0.5 SD, 1 SEM, and 2 SEM. Anchor-based methods assessed the relationship of differences in ACT scores to (1) self-reported asthma severity, (2) asthma episode frequency in the past 4 weeks, (3) physician ratings of asthma control, (4) physician recommendation of a change in therapy, (5) FEV(1), (6) the risk over the next 12 months of excess short-acting beta-agonist use and exacerbations, and (7) patient-defined changes in asthma course over 3 months. RESULTS: Four thousand one hundred eighteen patients completed the ACT. The 0.5 SD criterion for MID ranged from 2.03 to 2.45 points (mean, 2.2 points). The 1 SEM criterion ranged from 1.77 to 2.05 points (mean, 1.88 points), and the 2 SEM criterion ranged from 3.55 to 4.10 points (mean, 3.75 points). Differences in mean ACT scores across patient groups differing on criterion measures ranged from 1.06 to 5.28 points (mean, 3.1 points). Predictive analyses showed that a difference of 3 points on the ACT was associated with a subsequent 76% increased risk (95% CI, 73% to 79%) of excess short-acting beta-agonist use and a 33% increased risk (95% CI, 31% to 35%) of exacerbations. CONCLUSION: The data support an MID for the ACT of 3 points.