Methods for constructing and assessing propensity scores.
OBJECTIVE
To model the steps involved in preparing for and carrying out propensity score analyses by providing step-by-step guidance and Stata code applied to an empirical dataset.


METHODS
Guidance, Stata code, and empirical examples are given to illustrate (1) the process of choosing variables to include in the propensity score; (2) balance of propensity score across treatment and comparison groups; (3) balance of covariates across treatment and comparison groups within blocks of the propensity score; (4) choice of matching and weighting strategies; (5) balance of covariates after matching or weighting the sample; and (6) interpretation of treatment effect estimates.
We use data from the Palliative Care for Cancer Patients (PC4C) study, a multisite observational study of the effect of inpatient palliative care on patient health outcomes and health services use, to illustrate the development and use of a propensity score.


CONCLUSIONS
Propensity scores are one useful tool for accounting for observed differences between treated and comparison groups. Careful testing of propensity scores is required before using them to estimate treatment effects.
GRECC, James J Peters VA Medical Center, Bronx, NY; Brookdale Department of Geriatrics and Palliative Medicine, Icahn School of Medicine at Mount Sinai, New York, NY.
Melissa M
MM
Garrido
Amy S
AS
Kelley
Julia
J
Paris
Katherine
K
Roza
Diane E
DE
Meier
R Sean
RS
Morrison
Melissa D
MD
Aldridge
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002173:Cancer Care Facilities / Q000706:statistics & numerical data*; D015986:Confounding Factors, Epidemiologic; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009369:Neoplasms / Q000453:epidemiology; D009518:New York; D009820:Ohio; D017063:Outcome Assessment, Health Care / Q000379:methods*; D010166:Palliative Care / Q000706:statistics & numerical data*; D010414:Pennsylvania; D057216:Propensity Score; D012107:Research Design; D016896:Treatment Outcome; D014768:Virginia; D014922:Wisconsin; D055815:Young Adult
Observational data/quasi-experiments; administrative data uses; patient outcomes/function