Outcomes of patients receiving maintenance dialysis admitted over weekends

Abstract

Background: Hospital admissions over weekends have been associated with worse outcomes in different patient populations. The cause of this difference in outcomes remains unclear; however, different staffing patterns over weekends have been speculated to contribute. We evaluated outcomes in patients on maintenance dialysis therapy admitted over weekends using a national database.

Study design: Retrospective cohort study.

Setting & participants: We included nonelective admissions of adult patients (≥18 years) on maintenance dialysis therapy (n = 3,278,572) identified using appropriate International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for 2005-2009 using the Nationwide Inpatient Sample database.

Predictor: Weekend versus weekday admission.

Outcomes: The primary outcome measure was all-cause in-hospital mortality. Secondary outcomes included mortality by day 3 of admission, length of hospital stay, time to death, and discharge disposition.

Measurements: We adjusted for patient and hospital characteristics, payer, year, comorbid conditions, and primary discharge diagnosis common to maintenance dialysis patients.

Results: There were an estimated 704,491 admissions over weekends versus 2,574,081 over weekdays. Unadjusted all-cause in-hospital mortality was 40,666 (5.8%) for weekend admissions in comparison to 138,517 (5.4%) for weekday admissions (P < 0.001). In a multivariable model, patients admitted over weekends had higher all-cause in-hospital mortality (OR, 1.06; 95% CI, 1.01-1.10) in comparison to those admitted over weekdays and higher mortality during the first 3 days of admission (OR, 1.18; 95% CI, 1.10-1.26). Patients admitted over weekends were less likely to be discharged to home, had longer hospital stays, and had shorter times to death compared with those admitted over weekdays on adjusted analysis.

Limitations: Use of ICD-9-CM codes to identify patients, defining weekend as midnight Friday to midnight Sunday.

Conclusions: Maintenance dialysis patients admitted over weekends have increased mortality rates and longer lengths of stay compared with those admitted over weekdays. Further studies are needed to identify the reasons for worse outcomes for weekend admissions in this patient population.

Keywords: Dialysis; admissions; mortality.

Fig 1. Selection of study population (Age ≥18 year). Estimates from weighted survey data

Fig 2

Odds ratio and 95% confidence intervals for all-cause inpatient mortality associated with weekend admissions (vs. weekday admissions) in different subgroups. *OR of all-cause inpatient mortality are significantly different within subgroups of hospitals by teaching status using generalized Hausman Test (p=0.006)