Trends and transient change in end-digit preference in blood pressure recording: Studies of sequential and longitudinal collected primary care data
Alsanjari ON., De Lusignan S., Van Vlymen J., Gallagher H., Millett C., Harris K., Majeed A.
Background: End-digit preference (EDP) is a known cause of inaccurate BP recording. Distortion has been reported around pay-for-performance (P4P) indicators. Methods: We studied sequential datasets (n = 148,000 to n = 900,000) and performed a longitudinal analysis of CONDUIT data (n = 250,000) over a 10-year period. We examined general trends in EDP and investigated the impact of diabetes and chronic kidney disease (CKD) P4P targets. Results: EDP reduces over time in both datasets; the percentage of patients with a zero EDP declined from 70% to 27% and 68% to 26% for SBP and DBP respectively. There is more zero EDP at the extremes of BP, but in people with chronic disease, the use of zero EDP was mainly seen at higher BP levels. P4P targets are associated with increased preference for the even end-digit just below target: in diabetes odds ratio (OR) is 1.47 (p = 0.003) for SBP, 1.19 (p = 0.09) for DBP and in CKD OR 1.65 (p < 0.001) for SBP and 1.48 (p = 0.0001) for DBP. Trends observed in pilot data were validated with a longitudinal set. Conclusions: The decline in EDP is levelling off and P4P targets are associated with sub-target-EDP. Primary care should automate BP measurement and recording. © 2011 Blackwell Publishing Ltd.