Functional impairment as an outcome predictor in elderly patients

Functional impairment in daily activities is prevalent among elderly patients and population with chronic kidney disease and it may influence on their prognosis. This study investigated the association between activities of daily living (ADL) and instrumental activities of daily living (IADL) scores with incident renal replacement therapy (RRT) and mortality.

This retrospective cohort study included 6,087 individuals aged ≥65 years (2,737 men and 3,350 women) who underwent geriatric assessments including ADL and IADL at a Korean university hospital between January 2016 and December 2020. Participants exhibited an estimated glomerular filtration rate (eGFR) >15 ml/min/1.73m² and were followed for more than three months. ADL and IADL were evaluated using the Barthel Index and Lawton-Brody Index, respectively. The analyses were conducted separately for males and females due to gender-specific differences in IADL scale scores.

Participants aged 78.7 ± 6.0 years had eGFR 75.8 ± 19.4 ml/min/1.73m² at the point of test. Over a median follow-up period of 42 months, 2,108 participants (34.6%) died and 103 (1.7%) required RRT. The AUCs by ROC analysis showed reverse relationship between ADL or IADL and possibility of incident RRT or mortality in each gender (all p-values for estimating RRT in both gender <0.01, all p-values for estimating mortality in both gender <0.001). In men, abnormal IADL scores (<5) significantly increased the risk of RRT (HR 2.097, p=0.024), whereas abnormal ADL scores (<100) were not related to the risk (HR 1.612, p=0.145). Abnormal IADL was associated with a 68.9% increased risk of mortality (HR 1.689, p<0.001) and abnormal ADL increased the mortality risk by 41.5% (HR 1.415, p<0.001). In the analysis grouped by age and eGFR, younger men (<75 years) exhibited a significantly higher risk of RRT with abnormal ADL and IADL (ADL: HR, 13.931; IADL: HR, 14.237; both p<0.001) than older men (≥75 years) (ADL: HR 2.894, p<0.001; IADL: HR 3.445, p<0.001). Abnormal ADL and IADL were also associated with an increased risk of RRT in men with both higher (eGFR ≥75 ml/min/1.73 m2) (ADL: HR 4.164, p=0.004; IADL: HR 5.302, p<0.001) and lower renal function (eGFR <75 ml/min/1.73 m2) (ADL: HR 4.133, p<0.001; IADL: HR 4.220, p<0.001). Furthermore, abnormal ADL and IADL were significantly related with increased mortality risk in both younger and older men (p<0.001). Participants grouped by eGFR, the correlations between ADL and IADL and outcomes remained significant (p<0.001). In women, abnormal IADL scores (<8) were not associated with an increased risk of RRT (HR 1.634, p=0.231) and impaired ADL scores (<100) showed borderline significance for an increased risk of RRT (HR 2.078, p=0.065). However, abnormal IADL was associated with a increased risk of mortality (HR 2.016, p<0.001) and abnormal ADL was also related to the mortality risk (HR 2.158, p<0.001). In subgroup analysis, abnormal ADL and IADL scores were significantly correlated with mortality risk in both younger (p<0.001) or older women (p<0.001) and, in women with higher eGFR (≥75 ml/min/1.73 m2) (p<0.001) or lower eGFR (<75 ml/min/1.73 m2) (p<0.001).

ADL and IADL are critical predictors of RRT, especially in elderly men, and mortality in elderly patients. Association between mortality and functional impairment were more evident in younger elder persons (aged between 65 and 74 years).