Accelerometer-measured physical activity and functional behaviours among people on dialysis.

BACKGROUND: The feasibility of wrist-worn accelerometers, and the patterns and determinants of physical activity, among people on dialysis are uncertain. METHODS: People on maintenance dialysis were fitted with a wrist-worn AxivityAX3 accelerometer. Subsets also wore a 14-day electrocardiograph patch (Zio®PatchXT) and wearable cameras. Age-, sex- and season-matched UK Biobank control groups were derived for comparison. RESULTS: Median (interquartile range) accelerometer wear time for the 101 recruits was 12.5 (10.4-13.5) days, of which 73 participants (mean age 66.5 years) had excellent wear on both dialysis and non-dialysis days. Mean (standard error) overall physical activity levels were 15.5 (0.7) milligravity units (mg), 14.8 (0.7) mg on dialysis days versus 16.2 (0.8) mg on non-dialysis days. This compared with 28.1 (0.5) mg for apparently healthy controls, 23.4 (0.4) mg for controls with prior cardiovascular disease (CVD) and/or diabetes mellitus and 22.9 (0.6) mg for heart failure controls. Each day, we estimated that those on dialysis spent an average of about 1 hour (h/day) walking, 0.6 h/day engaging in moderate-intensity activity, 0.7 h/day on light tasks, 13.2 h/day sedentary and 8.6 h/day asleep. Older age and self-reported leg weakness were associated with decreased levels of physical activity, but the presence of prior CVD, arrhythmias and listing for transplantation were not. CONCLUSIONS: Wrist-worn accelerometers are an acceptable and reliable method to measure physical activity in people on dialysis and may also be used to estimate functional behaviours. Among people on dialysis, who are broadly half as active as general population controls, age and leg weakness appear to be more important determinants of low activity levels than CVD.

Declining comorbidity-adjusted mortality rates in English patients receiving maintenance renal replacement therapy.

We aimed to compare long-term mortality trends in end-stage renal disease versus general population controls after accounting for differences in age, sex and comorbidity. Cohorts of 45,000 patients starting maintenance renal replacement therapy (RRT) and 5.3 million hospital controls were identified from two large electronic hospital inpatient data sets: the Oxford Record Linkage Study (1965-1999) and all-England Hospital Episode Statistics (2000-2011). All-cause and cause-specific three-year mortality rates for both populations were calculated using Poisson regression and standardized to the age, sex, and comorbidity structure of an average 1970-2008 RRT population. The median age at initiation of RRT in 1970-1990 was 49 years, increasing to 61 years by 2006-2008. Over that period, there were increases in the prevalence of vascular disease (from 10.0 to 25.2%) and diabetes (from 6.7 to 33.9%). After accounting for age, sex and comorbidity differences, standardized three-year all-cause mortality rates in treated patients with end-stage renal disease between 1970 and 2011 fell by about one-half (relative decline 51%, 95% confidence interval 41-60%) steeper than the one-third decline (34%, 31-36%) observed in the general population. Declines in three-year mortality rates were evident among those who received a kidney transplant and those who remained on dialysis, and among those with and without diabetes. These data suggest that the full extent of mortality rate declines among RRT patients since 1970 is only apparent when changes in comorbidity over time are taken into account, and that mortality rates in RRT patients appear to have declined faster than in the general population.

Biliary Tract and Liver Complications in Polycystic Kidney Disease.

Polycystic liver disease is a well described manifestation of autosomal dominant polycystic kidney disease (ADPKD). Biliary tract complications are less well recognized. We report a 50-year single-center experience of 1007 patients, which raised a hypothesis that ADPKD is associated with biliary tract disease. We tested this hypothesis using all England Hospital Episode Statistics data (1998-2012), within which we identified 23,454 people with ADPKD and 6,412,754 hospital controls. Hospitalization rates for biliary tract disease, serious liver complications, and a range of other known ADPKD manifestations were adjusted for potential confounders. Compared with non-ADPKD hospital controls, those with ADPKD had higher rates of admission for biliary tract disease (rate ratio [RR], 2.24; 95% confidence interval [95% CI], 2.16 to 2.33) and serious liver complications (RR, 4.67; 95% CI, 4.35 to 5.02). In analyses restricted to those on maintenance dialysis or with a kidney transplant, RRs attenuated substantially, but ADPKD remained associated with biliary tract disease (RR, 1.19; 95% CI, 1.08 to 1.31) and perhaps with serious liver complications (RR, 1.15; 95% CI, 0.98 to 1.33). The ADPKD versus non-ADPKD RRs for biliary tract disease were larger for men than women (heterogeneity P<0.001), but RRs for serious liver complications appeared higher in women (heterogeneity P<0.001). Absolute excess risk of biliary tract disease associated with ADPKD was larger than that for serious liver disease, cerebral aneurysms, and inguinal hernias but less than that for urinary tract infections. Overall, biliary tract disease seems to be a distinct and important extrarenal complication of ADPKD.