What is an acceptable rate of VTE prophylaxis?

According to the paper “Hospital Performance for Pharmacologic Venous Thromboembolism Prophylaxis and Rate of Venous Thromboembolism: A Cohort Study” that appeared online in JAMA Internal Medicine last month, a rate of 70% for all eligible patients is good enough.

The retrospective study looked at rates of prophylaxis for VTE at 35 Michigan hospitals.

Of the 20,794 eligible patients included in the analysis, 1,658 either died or were transferred to higher or lower levels of care leaving 19,136 evaluable patients, 226 (1.2%) of whom suffered a VTE during either the hospitalization or the 90-day follow-up period.

Based on rates of prophylaxis administered, the hospitals were divided into three groups with 85.8% of patients receiving adequate prophylaxis in high-performance hospitals, 72.6% in moderate-performance hospitals, and 55.5% in low-performance hospitals.

From the results section of the paper: "Compared with patients at hospitals in the highest-performance tertile, the hazard of VTE in patients at hospitals in moderate-performance (hazard ratio, 1.10; 95% CI, 0.74-1.62) and low-performance (hazard ratio, 0.96, 95% CI, 0.63-1.45) tertiles did not differ after adjusting for potential confounders."

The authors concluded that "Efforts to increase rates of pharmacologic VTE prophylaxis in hospitalized medical patients may not substantively reduce this adverse outcome."

Here's the problem. They defined adequate rates as patients receiving pharmacologic prophylaxis during 80% or more of hospital-days such as "1 of 1 dose for daily regimens, 2 of 2 doses for twice daily regimens, or 2 of 3 doses for 3 times daily regimens.”

This means that patients could be classified as receiving appropriate prophylaxis but miss nearly half of their doses. For example, a patient in hospital for 5 days who got 2 of 3 doses for 4 days and missed all 3 on one day would be classified as having received appropriate prophylaxis. Why do the authors give full credit for delivering such low quality care? Why is missing any doses acceptable?

Does missing doses matter?

"Yes," at least in surgical patients, says this JAMA Surgery paper "Correlation of Missed Doses of Enoxaparin with Increased Incidence of Deep Vein Thrombosis in Trauma and General Surgery Patients."

Missing more than one dose of enoxaparin increased DVT risk significantly, and the more doses that were missed, the more DVTs occurred.

Of the 202 patients studied, 119 (58.9%) missed at least one dose of prophylactic enoxaparin. The overall incidence of DVT was 15.8%, but 23.5% of the patients who missed at least one dose developed a DVT compared to 4.8% of patients whose prophylaxis was never interrupted. Patients were aggressively screened for DVT accounting for a higher incidence than most centers report.

Missing 2-4 doses increased the odds ratio of suffering a DVT to 8.49, missing 5 to 8 doses raised it to 10.13, and the odds ratio rose to 14.73 if 9-17 doses were missed.

Among all 35 hospitals in the internal medicine paper, the rate of DVT prophylaxis for eligible patients was only 70%. The authors of that paper seem to think that is not worth improving. Wouldn't 100% compliance be a better goal?

What do you think?