A statewide evaluation of seven strategies to reduce opioid overdose in North Carolina

Abstract

Background: In response to increasing opioid overdoses, US prevention efforts have focused on prescriber education and supply, demand and harm reduction strategies. Limited evidence informs which interventions are effective. We evaluated Project Lazarus, a centralised statewide intervention designed to prevent opioid overdose.

Methods: Observational intervention study of seven strategies. 74 of 100 North Carolina counties implemented the intervention. Dichotomous variables were constructed for each strategy by county-month. Exposure data were: process logs, surveys, addiction treatment interviews, prescription drug monitoring data. Outcomes were: unintentional and undetermined opioid overdose deaths, overdose-related emergency department (ED) visits. Interrupted time-series Poisson regression was used to estimate rates during preintervention (2009-2012) and intervention periods (2013-2014). Adjusted IRR controlled for prescriptions, county health status and time trends. Time-lagged regression models considered delayed impact (0-6 months).

Results: In adjusted immediate-impact models, provider education was associated with lower overdose mortality (IRR 0.91; 95% CI 0.81 to 1.02) but little change in overdose-related ED visits. Policies to limit ED opioid dispensing were associated with lower mortality (IRR 0.97; 95% CI 0.87 to 1.07), but higher ED visits (IRR 1.06; 95% CI 1.01 to 1.12). Expansions of medication-assisted treatment (MAT) were associated with increased mortality (IRR 1.22; 95% CI 1.08 to 1.37) but lower ED visits in time-lagged models.

Conclusions: Provider education related to pain management and addiction treatment, and ED policies limiting opioid dispensing showed modest immediate reductions in mortality. MAT expansions showed beneficial effects in reducing ED-related overdose visits in time-lagged models, despite an unexpected adverse association with mortality.

Keywords: Epidemiology; Outcome Evaluation; Poisoning; Surveillance; Time Series.

Figure 1

Monthly counts of outcomes before and during intervention, North Carolina, 2009–2014. Statewide, monthly counts of outpatient opioid analgesic (OA) prescriptions dispensed, opioid overdose mortality and overdose-related hospital emergency department (ED) visits. In subsequent modelling, OA prescriptions dispensed was treated as a covariate, while overdose was the outcome variable. Grey triangles represent the pre-intervention period used in models (January 2009 to February 2013) and the black dots represent the intervention period (March 2013 to December 2014). By the end of the intervention period, the intervention was implemented in 74 of 100 counties, representing 70% of the total population.

Figure 2

Effects of implementing intervention strategies on overdose mortality and overdose-related emergency department (ED) visits. The outcome for A and B are overdose mortality and overdose-related ED visits, respectively. Results from multivariate regression models considered all seven intervention strategies simultaneously, after adjusting for the rate of opioid analgesic prescriptions, county health status, annual trends and seasonality. The models used to generate the figures used 0 for the referent group, and 1 for the implementation of the strategy, with indicator coding. IRRs (tables 1 and 2) were converted to percent change, represented by open circles. The horizontal bars are the model-based 95% CI. The grey vertical line represents the null.

Figure 3

Effects of implementing intervention strategies in time-lagged regression models of delayed impact of intervention.The vertical axis is percent change in overdose rates between intervention and non-intervention counties; the outcome in A is overdose mortality and B is overdose-related emergency department (ED) visits. Results from time-lagged (0 to 6 months) multivariate regression models considered all seven intervention strategies simultaneously, after adjusting for the rate of opioid analgesic prescriptions and county health status. AT, greater utilisation of addiction treatment; CE, community education; DC, diversion control; NP, take-home naloxone policies; PE, prescriber education on pain management and addiction; PP, support programme for patients with pain.