Issue:

The study compared opioid usage and prescribing patterns between WCB claimants and other Manitobans to identify potential problems or issues of opioid use among WCB claimants

Objectives:

• To identify what proportion of chronic opioid use for non-cancer pain in Manitoba is related to WCB compensable injuries.
• To compare opioid use in WCB claimants before, during, and after a WCB claim.
• To compare opioid duration and dose amongst WCB claimants with other Manitobans after controlling for demographic and diagnostic factors.

Anticipated Results:

Results of Study- completed in 2014
The project report outlined more than twenty findings and conclusions.
Dosage

• While WCB claimants accounted for 2.1% of all individuals that were prescribed opioids, 3.8% of total dosage was prescribed to WCB claimants.
• WCB claimants had higher mean opioid doses than other Manitobans.
• WCB claimants were approximately 20% more likely than other Manitobans to be prescribed more than 80 ME per day, and approximately twice as likely to be prescribed 120 ME or more per day.
• WCB claimants who had back surgeries were about eight times more likely than those who had knee surgeries to be prescribed more than 80 ME per day.
Duration
• WCB claimants had longer duration of continuous usage of opioids than other Manitobans.
• Even for shorter term prescriptions, there was a higher percentage of WCB claimants (19%) with more than three months of continuous use compared with 11% for other Manitobans.
• WCB claimants were more likely to be prescribed opioids for longer than 12 months.
• WCB claimants had longer durations of opioid use than other Manitobans and were more likely to be on high dose opioids.
• Longer periods of continuous use were associated with much higher levels of prescribed opioids.
• Dosage during a claim was related to the claim duration, as claimants with longer claims were generally prescribed higher doses over time.
• There was a strong association between the dosage and duration of use at the end of claim, and the dosage and duration of use post-claim.
• Among WCB claimants, duration of use pre-claim and during a claim were associated with duration of use post-claim.
• Among WCB claimants on more than 120 ME per day at the end of the claim, there was a decrease in the proportion taking opioids over time, with 20-30% of individuals coming off opioids in one year. However, many stayed on high doses of these medications.
• There is strong evidence that opioid dose and duration during a WCB claim, whether paid for or not paid by the WCB, influence the likelihood of post-claim opioid use, post-claim dose, and the post-claim duration of use.
• In the analysis of December 2010 data, 2.1% of the study group prescribed opioids were WCB claimants.
• Of these WCB claimants, 3.3% were male and 1.1% female.
Trends over Time
• The percentage of all opioid prescribed to WCB claimants peaked at 4.4% of the study group in 2008 before falling to 3.8% in 2010.
• The percentage of the study group prescribed opioids who were WCB claimants peaked at 2.5% in 2006 (n = 2605) before falling to 2.0% in 2010 (n = 2143).
• The average amount of opioid prescribed per person per year rose dramatically over time in both groups, but more so in the WCB group.
• From 1998 to 2010, there was a significant rise in the average yearly amount of opioid prescribed for the entire study group, though the increase was steeper among WCB claimants.
• The WCB claimants’ contribution to opioid usage in Manitoba began to decline in 2008 due to a smaller number of individuals receiving opioids and not a decrease in the average amount prescribed per recipient.
• The decrease in the number of WCB opioid claimants corresponded to a decrease in the number of time loss claims, which account for 90% of the WCB claimants in the study population.
• On average, the WCB paid for 94.5% of the ME prescribed to WCB claimants claimants during the claim period. However this varied with the total ME prescribed, as the higher the total MEs prescribed and the longer claim duration, the higher the percentage of opioids that were not covered by the WCB.
• Dosage during a claim was related to the claim duration, as claimants with longer claims were generally prescribed higher doses over time.
• Among WCB claimants, both opioids paid for and not paid for by the WCB were associated with average opioid dose during the first year post-claim.
• To reduce possible adverse health consequences of sustained opioid use, physicians and WCBs should work together to ensure proper dosing of opioids to control pain from work-related injuries.

Investigators:

Allen Kraut, MD,FRCPC, Leigh Anne Shafer, PhD; University of Manitoba; Colette B. Raymond, PharmD, MSc. Manitoba Center for Health Policy, University of Manitoba