Failed Target Weight Achievement Associates with Short-Term Hospital Encounters among Individuals Receiving Maintenance Hemodialysis

Abstract

Background Hospitalizations and 30-day readmissions are common in the hemodialysis population. Actionable clinical markers for near-term hospital encounters are needed to identify individuals who require swift intervention to avoid hospitalization. Aspects of volume management, such as failed target weight (i.e, estimated dry weight) achievement, are plausible modifiable indicators of impending adverse events. The short-term consequences of failed target weight achievement are not well established.Methods Statistically deidentified data were taken from a cohort of Medicare-enrolled, prevalent hemodialysis patients treated at a large dialysis organization from 2010 to 2012. We used a retrospective cohort design with repeated intervals, each consisting of 180-day baseline, 30-day exposure assessment, and 30-day follow-up period, to estimate the associations between failed target weight achievement and the risk of 30-day emergency department visits and hospitalizations. We estimated adjusted risk differences using inverse probability of exposure weighted Kaplan-Meier methods.Results A total of 113,561 patients on hemodialysis contributed 788,722 study intervals to analyses. Patients who had a postdialysis weight >1.0 kg above the prescribed target weight in ≥30% (versus <30%) of exposure period treatments had a higher absolute risk (risk difference) of 30-day: emergency department visits (2.13%; 95% confidence interval, 2.00% to 2.32%); and all-cause (1.47%; 95% confidence interval, 1.34% to 1.62%), cardiovascular (0.31%; 95% confidence interval, 0.24% to 0.40%), and volume-related (0.15%; 95% confidence interval, 0.11% to 0.21%) hospitalizations.Conclusions In the absence of objective measures of volume status, recurrent failure to achieve target weight is an easily identifiable clinical risk marker for impending hospital encounters among patients on hemodialysis.

Keywords: ED visits; hemodialysis; hospitalizations; target weight.

Figure 1.

Study designs. (A) In primary and secondary analyses, a retrospective cohort design with repeated intervals, each consisting of a 180-day baseline, a 30-day exposure assessment and a 30-day follow-up period was used. Exposure periods were anchored on eKt/V measurements occurring during the study period. This figure illustrates a single study interval; individuals could contribute multiple study intervals to analyses. Individual study intervals were constructed such that the: 1) exposure period began on the day after the indexing eKt/V measurement; 2) follow-up period began immediately after the end of the exposure period; and 3) baseline period for covariate ascertainment began 180 days prior to the start of the exposure period. (B) The study design for post hoc analyses involved identifying hospitalization events that occurred during 30-day follow-up intervals in the primary study. Exposure periods were anchored on hospital discharge dates. This figure illustrates a single study interval; individuals could contribute multiple study intervals to analyses. For each eligible hospitalization event the: 1) 7-day exposure period began on the day following hospital discharge; and 2) the follow-up period began immediately after the end of the exposure period and continued up to day 30 post-hospitalization. eKt/V, equilibrated kt/v; Rx, prescribed.

Figure 2.

Flow diagram depicting the assembly of the primary cohort. eKt/V, equilibrated kt/v.

Figure 3.

Associations between postdialysis weight above target weight in ≥30% versus <30% of exposure period treatments and 30-day all-cause hospital encounters across varying kilogram thresholds of failed target weight achievement. (A) Depicts the association between post-dialysis weight above the prescribed target weight in ≥30% versus <30% of exposure period treatments and 30-day all-cause ED visits across varying kilogram thresholds of failed target weight achievement. (B) Depicts the association between post-dialysis weight above the prescribed target weight in ≥30% versus <30% of exposure period treatments and 30-day all-cause hospitalizations across varying kilogram thresholds of failed target weight achievement. The null value for a risk difference is 0.00%. As the weight threshold for failure to attain target weight increased, the magnitude of the observed associations between postdialysis weight above the prescribed target weight and short-term hospital encounters also increased. ED, emergency department; ref., referent; wt, weight.

Figure 4.

Associations between having versus not having a prescribed target weight adjustment within 7 days of hospital discharge and 30-day posthospitalization outcomes. The null value for a risk difference is 0.00%. Individuals whose target weight was (versus was not) adjusted within 7 days of hospital discharge had lower risks of 30-day ED visits, all-cause hospitalizations, and the composite outcome. 95% CI, 95% confidence interval; ED, emergency department; ref., referent.