Quality of life in patients with diabetic nephropathy: findings from the KNOW-CKD (Korean Cohort Study for Outcomes in Patients with Chronic Kidney Disease) cohort

Abstract

Background: Diabetic nephropathy (DN) can affect quality of life (QoL) because it requires arduous lifelong management. This study analyzed QoL differences between DN patients and patients with other chronic kidney diseases (CKDs).

Methods: The analysis included subjects (n = 1,766) from the KNOW-CKD (Korean Cohort Study for Outcomes in Patients with Chronic Kidney Disease) cohort who completed the Kidney Disease Quality of Life Short Form questionnaire. After implementing propensity score matching (PSM) using factors that affect the QoL of DN patients, QoL differences between DN and non-DN participants were examined.

Results: Among all DN patients (n = 390), higher QoL scores were found for taller subjects, and lower scores were found for those who were unemployed or unmarried, received Medical Aid, had lower economic status, had higher platelet counts or alkaline phosphatase levels, or used clopidogrel or insulin. After PSM, the 239 matched DN subjects reported significantly lower patient satisfaction (59.9 vs. 64.5, p = 0.02) and general health (35.3 vs. 39.1, p = 0.04) than the 239 non-DN subjects. Scores decreased in both groups during the 5-year follow-up, and the scores in the work status, sexual function, and role-physical domains were lower among DN patients than non-DN patients, though those differences were not statistically significant.

Conclusion: Socioeconomic factors of DN were strong risk factors for impaired QoL, as were high platelet, alkaline phosphatase, and clopidogrel and insulin use. Clinicians should keep in mind that the QoL of DN patients might decrease in some domains compared with non-DN CKDs.

Keywords: Diabetic nephropathy; Kidney Disease Quality of Life Short Form questionnaire; Kidney disease component summary; Mental component summary; Physical component summary; Quality of life.

Figure 1.. Flow chart of the patients.

The analysis incorporated the 1,766 KNOW-CKD (Korean Cohort Study for Outcomes in Patients with Chronic Kidney Disease) subjects who completed the Kidney Disease Quality of Life Short Form (KDQOL-SF). After finding the factors that significantly influenced the kidney disease component summary, physical component summary, and mental component summary scores of subjects with diabetic nephropathy (DN) (n = 390), propensity score matching (PSM) using those factors yielded 239 DN and 239 non-DN subjects. Between-group differences in mean baseline and 5-year follow-up (FU) KDQOL-SF scores were analyzed. QoL, quality of life.

Figure 2.. Forest plot of linear regression for KDCS, PCS, and MCS scores in the DN group.

(A) Linear regression analyses of KDCS, PCS, and MCS scores and QoL-influencing factors were conducted. Lower KDCS scores were associated with short stature, unemployment, unmarried status, non-Medical Aid status, higher alkaline phosphatase levels, and clopidogrel use. (B) Lower PCS scores were associated with lower economic status, high platelet counts, high alkaline phosphatase levels, and clopidogrel use. (C) Lower MCS scores were associated with lower economic status and high platelet counts. BUN, blood urea nitrogen; DN, diabetic nephropathy; HbA1c, hemoglobin A1c; KDCS, kidney disease component summary; MCS, mental component summary; PCS, physical component summary; QoL, quality of life; ref., reference; RWT, relative wall thickness; TIBC, total iron binding capacity.

Figure 3.. Spider chart of baseline quality of life.

(A) Differences of each component of kidney disease component summary (KDCS) according to the two groups. (B) Differences of each component of mental component summary (MCS) and physical component summary (PCS) according to the two groups. (C) Summarizing KDCS, MCS, and PCS according to the two groups. Compared with the non-diabetic nephropathy (DN) group, the DN group had a significantly lower patient satisfaction score (p = 0.02), non-significantly lower scores for sexual function and work status, a significantly lower general health score (p = 0.04), and a non-significantly lower energy/fatigue score. The lower absolute scores in the DN group are shown by the containment of the solid line (DN) inside the graph. The DN group also had non-significantly lower KDCS, PCS, and MCS scores. ^aSignificant between-group difference.

Figure 4.. Spider chart of follow-up data.

(A) Differences of each component of kidney disease component summary (KDCS) according to the two groups. (B) Differences of each component of mental component summary (MCS) and physical component summary (PCS) according to the two groups. (C) Summarizing KDCS, MCS, and PCS according to the two groups. The diabetic nephropathy (DN) group had non-significantly lower work status, sexual function, role-physical domain, and composite scores. ^aSignificant between-group difference.

Figure 5.. Spider chart of QoL changes.

(A) Differences of each component of kidney disease component summary (KDCS) according to the two groups. (B) Differences of each component of mental component summary (MCS) and physical component summary (PCS) according to the two groups. (C) Summarizing KDCS, MCS, and PCS according to the two groups. Changes in QoL were analyzed in 221 participants who completed the 5-year follow-up QoL questionnaire. Relative to the gray circle marked 0, a positive value (outside) denotes decreased QoL, and a negative value (inside) indicates improved QoL. In both groups, several domain scores decreased over time, although the social support, patient satisfaction, and physician encouragement scores increased. The diabetic nephropathy (DN) patients had non-significantly greater decreases in the role-physical, social function, and role-emotional domains than non-DN patients. The composite scores decreased in both groups, with no statistically significant between-group difference. QoL, quality of life.