Geographic variation in rates of selected surgical procedures within Los Angeles County

We explore the contribution of income and ethnicity to geographic variation in utilization of surgical procedures.

We assessed the use of eight procedures from 1986 through 1988 among residents of Los Angeles County using data from the California Discharge Dataset, the 1980 census, and other secondary sources. Procedures chosen for evaluation were coronary artery bypass grafting (CABG), coronary artery angioplasty, permanent pacemaker insertion, mastectomy, simple hysterectomy, transurethral prostate resection (TURP), carotid endarterectomy, and appendectomy.

The amount of inter-zip code variation for each procedure was first measured using various estimates including the analysis of variance coefficient of variation (CVA). Population-weighted multivariate regression analysis was used to model variation in age- and gender-adjusted rates of procedure use among 236 residential zip codes.

Highest-variation procedures were coronary artery angioplasty (CVA = .392) and carotid endarterectomy (CVA = .374). The procedures with the lowest degree of variation were cardiac pacemaker implantation (CVA = .194) and hysterectomy (CVA = .195). Variation was significantly related to income (carotid endarterectomy) and either African American or Latino zip code ethnicity for all procedures except pacemaker implantation. For all procedures except appendectomy, the direction of the effect was toward fewer procedures with lower income. However, the effect of African American or Latino population ethnicity varied.

In this large urban area both population ethnicity and socioeconomic status are significantly associated with the geographic utilization of selected surgical procedures.