Nonadherence with Employer-Mandated Sleep Apnea Treatment and Increased Risk of Serious Truck Crashes

Abstract

Study objectives: To evaluate the effect of an employer-mandated obstructive sleep apnea (OSA) program on the risk of serious preventable truck crashes.

Methods: Data are from the first large-scale, employer-mandated program to screen, diagnose, and monitor OSA treatment adherence in the US trucking industry. A retrospective analysis of cohorts was constructed: polysomnogram-diagnosed drivers (OSA positive n = 1,613, OSA negative n = 403) were matched to control drivers unlikely to have OSA (n = 2,016) on two factors affecting crash risk, experience-at-hire and length of job tenure; tenure was matched on the date of each diagnosed driver's polysomnogram. Auto-adjusting positive airway pressure (APAP) treatment was provided to all cases (i.e. OSA positive drivers); treatment adherence was objectively monitored. Cases were grouped by treatment adherence: "Full Adherence" (n = 682), "Partial Adherence" (n = 571), or "No Adherence" (n = 360). Preventable Department-of-Transportation-reportable crashes/100,000 miles were compared across study subgroups. Robustness was assessed.

Results: After the matching date, "No Adherence" cases had a preventable Department of Transportation-reportable crash rate that was fivefold greater (incidence rate ratio = 4.97, 95% confidence interval: 2.09, 10.63) than that of matched controls (0.070 versus 0.014 per 100,000 miles). The crash rate of "Full Adherence" cases was statistically similar to controls (incidence rate ratio = 1.02, 95% confidence interval: 0.48, 2.04; 0.014 per 100,000 miles).

Conclusions: Nontreatment-adherent OSA-positive drivers had a fivefold greater risk of serious preventable crashes, but were discharged or quit rapidly, being retained only one-third as long as other subjects. Thus, the mandated program removed risky nontreatment-adherent drivers and retained adherent drivers at the study firm. Current regulations allow nonadherent OSA cases to drive at another firm by keeping their diagnosis private.

Commentary: A commentary on this article appears in this issue on page 961.

Keywords: APAP; CPAP; OSA; PSG; commercial motor vehicle operator; motor carrier; obstructive sleep apnea; preventable crash; screening; truckload.

Figure 1

Incidence rate ratios and hazard ratios by study subgroup. (A) Primary results, the rate of preventable crashes in each study subgroup per 100,000 miles driven compared to that of matched controls. (B) Results of the first of the three robustness tests, the hazard ratio for each study subgroup compared with that of matched controls in a multivariate Andersen-Gill time-to-event model on week-by-week data that controls for multiple factors affecting the risk of a crash such as miles per week, trips per week, and demographics. The interval covered is all weeks in which the subject is observed after the polysomnogram date (cases) or matching date (controls). Error bars are 95% confidence intervals. Significant differences between the control group and obstructive sleep apnea study subgroups are denoted as *P < 0.001.

Figure 2

Predicted cumulative hazard of a preventable DOT-reportable crash by study sub-group. The predicted cumulative risk of having a preventable DOT-reportable crash as a function of job tenure. For drivers who were inexperienced-at-hire and had a PSG/ matching date at 26 weeks of tenure, broken out by treatment compliance sub-groups for cases. Predictions are from the first robustness test model, the multivariate Andersen-Gill time-to-crash model on driver-week data.

Figure 3

Exit status during study period by study subgroup. Percentage of each subgroup in each status. “Still Employed” drivers remained at work as of the study end date of December 31, 2009. No Adherence drivers who failed in remediation were subject to eventual discharge, but some who received a diagnosis near the end of the study remain employed at study end because their remediation process was still underway. A higher proportion of No Adherence drivers quit than did drivers in other study subgroups (P < 0.001).