Abstract
Background and Aims
A growing number of patients treated with maintenance dialysis are older, frail and have functional impairment. In many instances, functional impairment is a more powerful predictor of adverse outcomes than traditional disease-based measures. The Kidney Disease Quality of Life 36-item short form survey (KDQOL-36) is widely used in dialysis patients; its scores are important predictor of outcome. Aim of the study is to evaluate the associations of KDQOL-36 scores with diabetes, dialysis modality, nutritional status and age in a cohort of dialysis patients from Chile.
Method
observational, multicenter, cross-sectional study performed in the region of Valparaiso, Chile. 207 adult patients on dialysis from more than 3 months (140 in HD, 67 in PD: mean age 58.9 ± 14.5 years with 37% >= 65 years, M/F 119/88) were asked to fill in the Spanish translation of the KDQOL-36 questionnaire (administered by a trained caregiver). The responses to the SF-36 questions were used to determine scores for the mental component summary (MCS), physical component summary (PCS), burden of kidney disease (BKD), symptoms and problems of kidney disease (SPKD), effects of kidney disease (EKD). The scores went from 0 to 100; the higher scores the better the quality of life. 50 was set as a cut-off level. Nutritional parameters were collected (BMI; mean 27.16 ± 4.7 kg/m2, brachial muscular or fat areas (< 25th percentile for age and sex defined as malnourished). All the patients signed an informed consent.
Results
Overall, mean scores and percentage of patients with values <50 on the PCS, MCS, BKD, SPKD, and EKD subscales were 45.54 ± 18.82 (60.9%), 57.38 ± 19.41 (36.2%), 73.43 ±18.33 (65.2%), 79.03 ±11.59 (1.9%), and 36.02 ± 34.74 (11.6%), respectively. The mean score of the combination of MCS and PCS was 51.46 ± 16.77 (52.2%).
Compared to younger patients, those who were 65 or more years old had significantly higher score of EKD (79.91 ± 16.63 vs 69.59 ± 18.26, p<0.0001), with only 12% of older patients having a score below 50 (Χ2 7.79, p=0.005); the other subscales did not differ significantly.
Ninety-one (43.5%) patients were diabetics. They were more likely of being older, having a higher BMI and lower signs of malnutrition (borderline significance). In comparison to non-diabetics, they had lower mean scores on BKD scale (30.42 ± 35.12 vs 40.4 ± 33.87, p=0.04) with a higher number having BKD scores < 50 (66/91 vs 69/116, Χ2 3.82, p=0.035). Moreover, they were more likely of having scores < 50 for the SPKD and EKD subscales.
A significant reduction of the muscular and fat brachial areas (<25th percentile) were found in 88 (42.1%) and 49 (23.4%) of the patients, respectively. Mean scores of all subscales did not differ significantly between the groups of muscular and fat brachial areas.
The dialysis modality had a significant impact on some subscales. in comparison to PD, a higher number of HD patients had scores < 50 for BKD (Χ2 18.24, p < 0.0001). On the other hand, PD patients were more likely of having lower MNS scores (Χ2 5.69, p < 0.013) and of the combination of PCS and MCS subscales (Χ2 12.82, p < 0.0001). Similar findings were obtained when analysing the scores as continuous variables.
Conclusion
This is the first formal evaluation of the performances of the KDQOL-36 questionnaire in a cohort of dialysis patients in Chile. Overall, the mean scores of PCS and EKD were well below the reference value of 50. General and kidney-related subscales were affected differently by age, dialysis modality and diabetes. In particular diabetic patients were more likely to perform poorly at kidney-related subscales, with no significant difference for general ones. Interestingly, dialysis modality had an impact on both BKD and MCS with opposite trends. The nutritional status seems to little affect patient quality of life.
Negligible impact of differential item functioning between Black and White dialysis patients on the Kidney Disease Quality of Life 36-item short form survey (KDQOLTM-36)
