Abstract 047: Variation by Provider in Echocardiographic Surveillance of Mitral Regurgitation

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Clinical outcomes after surgical treatment of mitral regurgitation (MR) are worse if intervention occurs after deterioration of left ventricular (LV) size and function. Echocardiographic surveillance of patients with MR is therefore indicated to avoid ventricular remodeling that could worsen patient outcomes. However, overly frequent trans-thoracic echocardiograms (TTEs) can impair access for other patients and reduce value in the delivery of care. Given the balance between timeliness of surveillance and possible over-utilization of TTE in valvular disease, we sought to investigate patient and provider factors contributing to variation in TTE utilization. We hypothesized that there was variation attributable to provider practice even after adjustment for patient characteristics.

We obtained records of all TTEs from 2001-2016 ordered at a large echocardiography laboratory. For each TTE, we linked to patient demographic data from hospital administrative records. To control for both clinical and demographic predictors of frequency of echocardiography, we constructed a hierarchical mixed-effects linear regression model with the individual physician as the random effect in the model. The outcome variable was time interval between TTEs. Intra-class correlation coefficient (ICC) was used to assess the proportion of total variation in the outcome variable due to provider practice, and shrinkage estimates were used to measure the contribution of individual providers.

After application of exclusion criteria, 79,194 TTEs corresponding to 55,663 TTE intervals remained. The mean interval between TTEs was 11.9 months for severe MR, 15.4 months for moderate MR, and 17.6 and 17.7 months for mild and trace MR respectively. After multivariate adjustment, male gender (Rate Ratio (RR) 0.96; 95% CI 0.94-0.98) was associated with shorter follow up, and Hispanic race (RR 1.11; 95% CI 1.01-1.21) was associated with longer follow-up intervals. Eight hundred and sixty-seven physicians were included in the analysis. After adjustment for patient factors, 31% of the variation in intervals was associated with provider practice and 19% of providers (161 of 867) were over-utilizers of TTEs and 24% (210 of 867) were under-utilizers.

We conclude that substantial variation exists in follow up intervals for TTE assessment of MR even after risk-adjustment for clinical and demographic variables, likely due to provider factors including specialty and experience. The association of TTE interval with race and gender warrants further investigation. Improving standardization of follow-up intervals may offer opportunity to reduce both overutilization and underutilization of echocardiography.

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