Can the wrong statistic be bad for health? Improving the reporting of door-to-needle time performance in acute myocardial infarction.

BACKGROUND: Current acute myocardial infarction (AMI) guidelines call for reperfusion to be given to all eligible patients within a set time interval after hospital arrival, yet current hospital performance benchmarks are based on the median door-to-intervention time among treated patients. Our objective is to compare hospital performance rankings when door-to-needle time (DNT) is measured at the current benchmark (median < or = 30 minutes) versus those obtained with more stringent benchmarks common for other AMI treatments. METHODS: A secondary analysis of data from the EFFECT study from 52 small, community and teaching hospitals in Ontario. All Ontario hospital corporations that treated > or = 30 patients with AMI from 1999 to 2001 participated. The charts of approximately 125 patients with AMI per hospital were reviewed; median and 85th percentile DNTs were then calculated for patients with ST-elevation AMI given thrombolysis at each site along with the proportion of patients thrombolysed within the recommended time. Hospitals were then ranked according to each indicator. RESULTS: Data were obtained on 1,578 patients given thrombolytic drugs at 52 hospitals. The median and 85th percentile DNTs were 37 and 82 minutes, respectively; the proportion of patients treated in < or = 30 minutes ranged from 8.5% to 60%. Hospitals that achieved a median DNT of < or = 30 minutes treated 40% to 50% of their patients outside that time frame. The ranks of the top 15 median DNT hospitals changed substantially when re-ranked according to the 85th percentile (average change in rank -16, range +6 to -40). If DNT improved such that a 30-minute median target was achieved, the estimated reduction for the average patient would be 13 minutes versus a 43-minute reduction if the 85th percentile target was achieved. CONCLUSION: Hospitals that achieve a 30-minute median DNT benchmark still treat 40% to 50% of their patients outside the recommended time, which is not consistent with current AMI treatment guidelines. Door-to-needle time for the average patient would be up to 43 minutes faster if the DNT target was achieved at the 85th percentile.