Identifying a cohort of patients with early-stage breast cancer - A comparison of hospital discharge and primary data

BACKGROUND. Hospital discharge data are a potential source of information f or quality of care; however, they lack detailed clinical data. OBJECTIVES. To assess the usefulness of hospital discharge data for describ ing patterns of care. RESEARCH DESIGN. Cohort study comparing hospital discharge data with data c ollected from medical records and patients. PATIENTS. Women diagnosed with early-stage breast cancer in Massachusetts a nd Minnesota (1993-1995). MEASURES. The percentage of patients in the primary data set who did not ma tch a record in the discharge data set, and the percentage of patients in t he discharge data set who did not match a record in the primary data set. O dds ratios for appearing in one data set, but not the other according to pa tient and hospital characteristics. RESULTS. For patients in the primary data set, 26.9% from Massachusetts and 13.2% from Minnesota did not match a record in the discharge data set. In both states, factors associated with failure to match to the discharge data included receipt of breast conserving surgery, shorter length of stay, and treatment hospital. For patients in the discharge data set, 43.4% in Massa chusetts and 30.3% in Minnesota did not match a patient in the primary data set. In both states, factors associated with failure to match to the prima ry data included treatment hospital and the presence of positive lymph node s. CONCLUSIONS. Hospital discharge data were fairly sensitive when linked to p atients with early-stage breast cancer who were identified through hospital records. The discharge data lacked specificity, however. If discharge data are used to characterize patterns care for inpatients with early stage dis ease, estimates are likely to be inaccurate due to the inclusion of unsuita ble patients in the denominator used to calculate procedure rates.