Refining physician quality indicators for screening mammography in older women: distinguishing appropriate use from overuse

Abstract

Objectives: To assess the feasibility of refining physician quality indicators of screening mammography use based on patient life expectancy.

Design: Retrospective population-based cohort study.

Setting: Texas.

Participants: Three thousand five hundred ninety-five usual care providers (UCPs) with at least 10 female patients aged 67 and older on January 1, 2008, with an estimated life expectancy of 7 years or more (222,584 women) and at least 10 women with an estimated life expectancy of less than 7 years (90,903 women), based on age and comorbidity.

Measurements: Screening mammography use in 2008-09 by each provider in each population.

Results: The average adjusted mammography screening rates for UCPs were 31.1% for women with a life expectancy of less than 7 years and 55.2% for women with a life expectancy of 7 years or longer. For women with limited life expectancy, 3.7% of UCPs had significantly lower and 9.2% had significantly higher than average adjusted mammography screening rates. For women with longer life expectancy, 16.7% of UCPs had significantly lower and 19.7% had significantly higher than average rates. UCP adjusted screening rates were stable over time (2006-07 vs 2008-09, correlation coefficient (r) = 0.65, P < .001). There was a strong correlation between UCP screening rates for their female patients with a life expectancy of less than 7 years and 7 years or longer (r = 0.67, P < .001). Most physician characteristics associated with higher screening rates (e.g., being female and foreign trained) in women with longer life expectancy were also associated with higher screening rates in women with limited life expectancy.

Conclusion: Providers with high mammography screening rates for women with longer life expectancy also tend to screen women with limited life expectancy. Quality indicators for screening practice can be improved by distinguishing appropriate use from overuse based on patient life expectancy.

Figure 1

Cumulative distribution of 3595 usual care providers (UCPs) by the rates of screening mammography of their patients in 2008–09. Figure 1A includes the rates for women with an estimated life expectancy of <7 years and Figure 1B includes women with an estimated life expectancy of ≥7 years. Adjusted screening rates and 95% confidence intervals for each UCP are shown, derived from a multilevel null model. UCPs were ranked from 1 to 3595 (horizontal axis) by their screening rates (vertical axis). The UCP with a rank of one had the lowest screening rate, while the UCP with a rank of 3595 had the highest screening rate. UCPs with rates significantly different from the average are indicated with dark ink.

Figure 2

Scatterplot of rates for each usual care provider (UCP) of screening mammography for their patients with limited life expectancy (<7 years) vs. longer life expectancy (≥7 years). Each of the 3595 UCPs is represented by one point, indicating the mammography rates of their patients with limited (vertical axis) and longer life expectancies (horizontal axis) in 2008–2009. The plot is divided into four quadrants based on the average UCP screening rates for patients with longer and limited life expectancy. For example, UCPs in quadrant I have screening rates above the mean for women with limited life expectancy and below the mean for women with longer life expectancy. The rates were generated from multilevel null models. The Pearson correlation coefficient between the two rates is 0.67 (p<0.001).