Accuracy of Administrative Data for Identifying Patients With Pneumonia

TLDR

The study aimed to assess the accuracy and impact of five claims‑based pneumonia definitions. The authors compared three ICD‑9 and two DRG‑based algorithms to an independent clinical reference standard. Among 10,748 patients, only 2.5% had pneumonia by reference standard; claims‑based algorithms had sensitivities of 47.8–66.2% and PPVs of 72.6–80.8%, with ICD‑9 methods not altering patient characteristics but DRG methods showing lower admission, mortality, length of stay, and costs, indicating overall imprecision.

Abstract

The goal of this study was to determine the accuracy and the impact of 5 different claims-based pneumonia definitions. Three International Classification of Diseases, Version 9, (ICD-9), and 2 diagnosis-related group (DRG)-based case identification algorithms were compared against an independent, clinical pneumonia reference standard. Among 10748 patients, 272 (2.5%) had pneumonia verified by the reference standard. The sensitivity of claims-based algorithms ranged from 47.8% to 66.2%. The positive predictive values ranged from 72.6% to 80.8%. Patient-related variables were not significantly different from the reference standard among the 3 ICD-9-based algorithms. DRG-based algorithms had significantly lower hospital admission rates (57% and 65% vs 73.2%), lower 30-day mortality (5.0% and 5.8% vs 10.7%), shorter length of stay (3.9 and 4.1 days vs 5.6 days), and lower costs (US $4543 and US $5159 vs US $8585). Claims-based identification algorithms for defining pneumonia in administrative databases are imprecise. ICD-9-based algorithms did not influence patient variables in our population. Identifying pneumonia patients with DRG codes is significantly less precise.