0822 Frail Older Men With Nocturia are Disproportionately Affected by Excess Nocturnal Urine Production

Abstract

Abstract Introduction Nocturia is a risk factor for falls and hip fractures in older adults. We determined whether the Frailty Index (FI), incorporating comorbidities, functional performance, and physical signs, was associated with nocturia frequency and/or overnight urine production. Methods We examined nightly (24-hour) voiding diaries (men ≥65 years) in an outpatient urologic clinic demonstrating ≥2 nocturnal voids (n=158). FI calculations followed Rockwood (CMAJ 2005;173:489-95). A total of 39 conditions were assessed. Three FI groups were established: Low (≤0.077) (n=59), Intermediate (>0.077 and <0.179) (n=58), and High (≥0.179) (n=41). We compared number of nocturnal voids (NV), nocturnal urine volume (NUV) (in mL), and 24-hr total urine volume (24-hr TUV) (in mL) across groups. Results NV did not differ by group (p=0.333) (median for all groups=3). However, NUV (916 [671-1419] vs. 690 [505-942] vs. 630 [500-1050] mL) differentiated the High, Medium and Low FI groups (p<0.001 via Kruskal-Wallis with Bonferroni pairwise adjustments), respectively. Similarly, 24-hr TUV differentiated the 3 groups (2200 [1800-2550] vs. 1620 [1259-2119] vs. 1650 [1390-2517] mL, p=0.005). Differences in NUV remained significant (p=0.006) after eliminating Diabetes Mellitus cases (n=44). However, differences did not persist for 24-hr TUV (p=0.180). Conclusion Higher NUV, but not 24-hr TUV, was a robust correlate of frailty in these older men. Accounting for diabetes did not diminish the effect. Although undiagnosed sleep apnea remains a possible cause, recent chronobiologic data (Monaghan et al, Age Aging, 2020, in press) suggest that nocturia in the aged is characterized by excess free water clearance early in the sleep period. This argues against solute-driven urine production (as might be expected in sleep apnea) in accounting for the effect. Nocturia may represent a conspicuous and important change in circadian rhythm of urine production occurring in old age. Support N/A