Hidden Complexities in Assessment of Glycemic Outcomes

Abstract

OBJECTIVE: To evaluate facility rankings in achieving <7% A1C levels based on the complexity of glycemic treatment regimens using threshold and continuous measures. RESEARCH DESIGN AND METHODS: We conducted a retrospective administrative data analysis of Veterans Health Administration Medical Centers in 2003–2004. Eligible patients were identified using National Committee for Quality Assurance (NCQA) measure specifications. A complex glycemic regimen (CGR) was defined as receipt of insulin or three oral agents. Facilities were ranked using five ordinal categories based up both z score distribution and statistical significance (P < 0.05). Rankings using the NCQA definition were compared with a subset receiving CGRs using both a <7% threshold and a continuous measure awarding proportional credit for values between 7.9 and <7.0%. Ranking correlation was assessed using the Spearman correlation coefficient. RESULTS: A total of 203,302 patients (mean age 55.2 years) were identified from 127 facilities (range 480–5,411, mean 1,601); 26.7% (17.9–35.2%) were receiving CGRs, including 22.0% receiving insulin. Mean A1C and percent achieving A1C <7% were 7.48 and 48% overall and 8.32 and 24.8% for those receiving CGRs using the threshold measure; proportion achieved was 60.1 and 37.2%, respectively, using the continuous measure. Rank correlation between the overall and CGR subset was 0.61; 8 of 24 of the highest or lowest ranked facilities changed to nonsignificance status; an additional five sites changed rankings. CONCLUSIONS: Facility rankings in achieving the NCQA <7% measure as specified differ markedly from rankings using the CGR subset. Measurement for public reporting or payment should stratify rankings by CGR. A continuous measure may better align incentives with treatment intensity.