title: Dealing with missing data in observational health care outcome analyses.
abstract: Observational outcome analyses appear frequently in the health research literature. For such analyses, clinical registries are preferred to administrative databases. Missing data are a common problem in any clinical registry, and pose a threat to the validity of observational outcomes analyses. Faced with missing data in a new clinical registry, we compared three possible responses: exclude cases with missing data; assume that the missing data indicated absence of risk; or merge the clinical database with an existing administrative database. The predictive model derived using the merged data showed a higher C statistic (C = 0.770), better model goodness-of-fit as measured in a decile-of-risk analysis, the largest gradient of risk across deciles (46.3), and the largest decrease in deviance (-2 log likelihood = 406.2). The superior performance of the enhanced data model supports the use of this "enhancement" methodology and bears consideration when researchers are faced with nonrandom missing data.
authors.affiliation: The Alberta Provincial Project for Outcome Assessment in Coronary Heart Disease "Approach," 8111 1st Floor ABC, 8440-112 Street, Edmonton, Alberta, Canada. cnorris@approach.org
authors.forename: C M
authors.initials: CM
authors.lastname: Norris
authors.forename: W A
authors.initials: WA
authors.lastname: Ghali
authors.forename: M L
authors.initials: ML
authors.lastname: Knudtson
authors.forename: C D
authors.initials: CD
authors.lastname: Naylor
authors.forename: L D
authors.initials: LD
authors.lastname: Saunders
mesh_terms: D000328:Adult; D000416:Alberta; D006328:Cardiac Catheterization / Q000706:statistics & numerical data; D016208:Databases, Factual / Q000706:statistics & numerical data; D006801:Humans; D016015:Logistic Models; D017202:Myocardial Ischemia / Q000175:diagnosis; D016017:Odds Ratio; D017063:Outcome Assessment, Health Care / Q000379:methods* / Q000706:statistics & numerical data; D011785:Quality Assurance, Health Care / Q000706:statistics & numerical data; D012372:ROC Curve; D012042:Registries / Q000706:statistics & numerical data