Table 3.
SF-36 distributions of scores in the study sample (n=517 donors) vs. normative and healthy national sample comparators.
| SF-36 measure | Donors (n=517)
|
NHMS healthy cohort (n=868)a
|
Donors with poor, average, or superior scores relative to the normative mean in the general population of 50, % (n)
|
||||
|---|---|---|---|---|---|---|---|
| Meanb | SD | Meanb | SD | Poor (>5 points below) | Average (within 5 points) | Superior (>5 points above) | |
| Physical functioning | 54.3 | 6.0 | 54.8 | 5.7 | 7.5 (39) | 31.7 (164) | 60.7 (314) |
| Role – physical | 53.7c | 7.1 | 53.3 | 6.4 | 9.7 (50) | 17.8 (92) | 72.5 (374) |
| Bodily pain | 54.2* | 10.1 | 55.2* | 7.5 | 15.1 (78) | 22.8 (118) | 62.1 (321) |
| Vitality | 54.0* | 9.6 | 57.5* | 8.1 | 15.5 (80) | 31.9 (165) | 52.6 (272) |
| General health | 55.1* | 8.7 | 53.9c* | 7.4 | 11.8 (61) | 25.5 (132) | 62.7 (324) |
| Social functioning | 52.8* | 7.9 | 53.8* | 6.6 | 11.4 (59) | 17.6 (91) | 71.0 (367) |
| Role – emotional | 52.4c | 7.7 | 53.2d | 6.8 | 14.0 (72) | 11.8 (61) | 74.2 (383) |
| Mental health | 53.4* | 8.4 | 56.2* | 7.7 | 14.7 (76) | 27.9 (144) | 57.4 (297) |
| Physical component summary | 54.6c | 7.4 | 54.0d | 5.6 | 8.1 (42) | 27.7 (143) | 64.1 (331) |
| Mental component summary | 52.5c* | 8.7 | 55.1d* | 7.3 | 15.9 (82) | 32.9 (170) | 51.2 (264) |
NHMS, National Health Measurement Study; SD, standard deviation; SF-36, Short-Form-36
In a 2006 national sample of the noninstitutionalized US population aged 35–89 (n=3522)46 who completed telephone assessments of health-related quality of life, we selected all persons with the same upper age limit and same BMI range as in the living donor sample, and excluded all persons with any of 11 self-reported chronic diseases (coronary heart disease, stroke, diabetes, arthritis, eye disease, sleep disorder, respiratory disease, depression, ulcer, thyroid disease, back pain).
Scores were transformed to have a mean of 50 and an SD of 10 in the general population (i.e., norm-based scoring43). Higher scores indicate better HRQOL for all measures. All mean scores for the sample are significantly higher than SF-36 version 2 norms for the US general population (one-sample t-tests, all p values < .001). We used norm-based scoring in these analyses because it enables more accurate understanding of relative differences between subscale scores, e.g., whether scores on a given subscale are truly more favorable than scores on another subscales.43 Norm-based scoring is recommended by the scale designers.43 Because some studies of living donor HRQOL report 0–100 scoring rather than norm-based scoring, Table S2 in the Supplementary File provides donors’ scores computed with 0–100 scoring in order to allow comparison to other published living donor cohorts.
1 case was missing data.
2 cases were missing data.
Comparison of donors and NHMS healthy cohort members, 2-sample t tests, p < .05.