Modification of claims-based measures improves identification of comorbidities in non-elderly women undergoing mastectomy for breast cancer: a retrospective cohort study.

BACKGROUND: Accurate identification of underlying health conditions is important to fully adjust for confounders in studies using insurer claims data. Our objective was to evaluate the ability of four modifications to a standard claims-based measure to estimate the prevalence of select comorbid conditions compared with national prevalence estimates. METHODS: In a cohort of 11,973 privately insured women aged 18-64 years with mastectomy from 1/04-12/11 in the HealthCore Integrated Research Database, we identified diabetes, hypertension, deficiency anemia, smoking, and obesity from inpatient and outpatient claims for the year prior to surgery using four different algorithms. The standard comorbidity measure was compared to revised algorithms which included outpatient medications for diabetes, hypertension and smoking; an expanded timeframe encompassing the mastectomy admission; and an adjusted time interval and number of required outpatient claims. A χ2 test of proportions was used to compare prevalence estimates for 5 conditions in the mastectomy population to national health survey datasets (Behavioral Risk Factor Surveillance System and the National Health and Nutrition Examination Survey). Medical record review was conducted for a sample of women to validate the identification of smoking and obesity. RESULTS: Compared to the standard claims algorithm, use of the modified algorithms increased prevalence from 4.79 to 6.79 % for diabetes, 14.75 to 24.87 % for hypertension, 4.23 to 6.65 % for deficiency anemia, 1.78 to 12.87 % for smoking, and 1.14 to 6.31 % for obesity. The revised estimates were more similar, but not statistically equivalent, to nationally reported prevalence estimates. Medical record review revealed low sensitivity (17.86 %) to capture obesity in the claims, moderate negative predictive value (NPV, 71.78 %) and high specificity (99.15 %) and positive predictive value (PPV, 90.91 %); the claims algorithm for current smoking had relatively low sensitivity (62.50 %) and PPV (50.00 %), but high specificity (92.19 %) and NPV (95.16 %). CONCLUSIONS: Modifications to a standard comorbidity measure resulted in prevalence estimates that were closer to expected estimates for non-elderly women than the standard measure. Adjustment of the standard claims algorithm to identify underlying comorbid conditions should be considered depending on the specific conditions and the patient population studied.

Incidence of Surgical Site Infection Following Mastectomy With and Without Immediate Reconstruction Using Private Insurer Claims Data.

OBJECTIVE: The National Healthcare Safety Network classifies breast operations as clean procedures with an expected 1%-2% surgical site infection (SSI) incidence. We assessed differences in SSI incidence following mastectomy with and without immediate reconstruction in a large, geographically diverse population. DESIGN: Retrospective cohort study. PATIENTS: Commercially insured women aged 18-64 years with ICD-9-CM procedure or CPT-4 codes for mastectomy from January 1, 2004 through December 31, 2011 METHODS: Incident SSIs within 180 days after surgery were identified by ICD-9-CM diagnosis codes. The incidences of SSI after mastectomy with and without immediate reconstruction were compared using the χ2 test. RESULTS: From 2004 to 2011, 18,696 mastectomy procedures among 18,085 women were identified, with immediate reconstruction in 10,836 procedures (58%). The incidence of SSI within 180 days following mastectomy with or without reconstruction was 8.1% (1,520 of 18,696). In total, 49% of SSIs were identified within 30 days post-mastectomy, 24.5% were identified 31-60 days post-mastectomy, 10.5% were identified 61-90 days post-mastectomy, and 15.7% were identified 91-180 days post-mastectomy. The incidences of SSI were 5.0% (395 of 7,860) after mastectomy only, 10.3% (848 of 8,217) after mastectomy plus implant, 10.7% (207 of 1,942) after mastectomy plus flap, and 10.3% (70 of 677) after mastectomy plus flap and implant (P<.001). The SSI risk was higher after bilateral compared with unilateral mastectomy with immediate reconstruction (11.4% vs 9.4%, P=.001) than without (6.1% vs 4.7%, P=.021) immediate reconstruction. CONCLUSIONS: SSI incidence was twice that after mastectomy with immediate reconstruction than after mastectomy alone. Only 49% of SSIs were coded within 30 days after operation. Our results suggest that stratification by procedure type facilitates comparison of SSI rates after breast operations between facilities.