Variation in Chemotherapy Utilization in Ovarian Cancer: The Relative Contribution of Geography

Abstract

Objective. This study investigates geographic variation in chemotherapy utilization for ovarian cancer in both absolute and relative terms and examines area characteristics associated with this variation. Data Sources. Surveillance, Epidemiology, and End Results (SEER) Medicare data from 1990 to 2001 for Medicare patients over 65 with a diagnosis of ovarian cancer between 1990 and 1999. Chemotherapy within a year of diagnosis was identified by Medicare billing codes. The hospital referral region (HRR) represents the geographic unit of analysis. Study Design. A logit model predicting the probability of receiving chemotherapy by each of the 39 HRRs. Control variables included medical characteristics (patient age, stage, year of diagnosis, and comorbidities) and socioeconomic characteristics (race, income, and education). The variation among HRRs was tested by the w 2 statistic, and the relative contribution was measured by the o statistic. HHR market characteristic are then used to explain HRR-level variation. Principal Findings. The average chemotherapy rate was 56.6 percent, with a range by HRR from 33 percent to 67 percent. There were large and significant differences in chemotherapy use between HRRs, reflected by a w 2 for HRR of 146 (df 5 38, po.001). HRR-level variation in chemotherapy use can be partially explained by higher chemotherapy rates in HRRs with a higher percentage of hospitals with oncology services. However, an o analysis indicates that, by about 15 to one, the variation between patients in use of chemotherapy reflects variations in patient characteristics rather than unexplained variation among HRRs. Conclusions. While absolute levels of chemotherapy variation between geographic areas are large and statistically significant, this analysis suggests that the role of geography in determining who gets chemotherapy is small relative to individual medical characteristics. Nevertheless, while variation by medical characteristics can be medically justified, the same cannot be said for geographic variation. Our finding that density of oncology hospitals predicts chemotherapy use suggests that provider supply is positively correlated with geographic variation.

Increasing access to medical oncology consultation in older patients with stage II-IIIA non-small-cell lung cancer

“…These findings are consistent with previous studies of advanced and metastatic NSCLC [20,21] and of other cancers [22,23]. Lack of consensus may contribute to the geographic variation observed in this study as in others [11,24]. Radiation therapy was associated with medical oncology consultation, suggesting that patients receiving radiation were more likely to be seen by a multidisciplinary team that included a medical oncologist.…”

Race in ovarian cancer treatment and survival: a systematic review with meta-analysis

“…Of these, three [11,20,33] found significant differences in the receipt of treatment where four did not. These articles showed that African Americans have 0.44-0.66 times the odds of receiving treatment as whites.…”

“…Four studies reported on the receipt of chemotherapy (Table 2). Two found African Americans to be less like to receive chemotherapy than their white counterparts [33,35], when controlling for stage, age, education, and income. Cress et al found that African Americans have a higher proportion of chemotherapy alone (11.5% vs. 9.8%) without surgical intervention.…”

Regional variation in cancer‐directed surgery and mortality among women with epithelial ovarian cancer in the medicare population

“…Our findings with regard to chemotherapy were similar to those from another analysis that used SEERMedicare data (through 2001) to demonstrate variation in the use of chemotherapy for women with ovarian cancer in the Medicare population. 24 In that earlier study, the authors noted that clinical characteristics (stage at diagnosis, age, and comorbidities) were much more important than HRR in explaining chemotherapy use. However, those authors did report a range from 33% to 67% in the proportion of women who received chemotherapy across hospital referral regions in their analysis.…”