Claimant Characteristics
728 workers’ compensation claimants with MSK disorders were entered into 1 of 12 therapist clusters (MI group = 367, control group = 361). 74 claimants were excluded from the study due to medical reasons, non-compliance with their RTW program, or attendance in the RTW program for less than 5 days. For claimants who attended more than 1 RTW program during the study period, only data from the last completed RTW program was used since claimants at times are moved between programs until they are placed into the most appropriate program. A flow chart showing the enrollment, allocation, and analysis of claimants at each step of the study is shown in Fig. 2.
Table 1 presents a descriptive analysis of key claimant characteristics. Claimants were predominantly employed (72.7%), males (63.2%), in their mid 40–45 years (SD 12.2), married (39.6%), achieved a high school education, had an annual income of $59,800 CDN, with a disability duration of 233.7 days measured from date of accident to admission to RTW program, had moderate levels of pain and disability at program admission (mean pain VAS = 5.0/10 and mean Pain Disability Index = 48/70), and lower levels of pain and disability (mean pain VAS = 3.8/10 and mean Pain Disability Index = 35/70) at program discharge. No statistically significant differences were observed between claimants in the MI and control groups at program admission on claimant characteristics such as sex, marital status, income, education level, age, disability duration, pain intensity, or self-rated disability. A higher percentage of female claimants was observed in the control group versus the intervention group, however this was not statistically significant. There was a statistically significant difference in the percentage of claimants employed at time of referral to the RTW program between groups (p ≤ 0.01).
Table 1 Characteristics of claimants at referral for return-to-work program
When testing for a clustering effect, the claimant characteristics that were statistically different (p < 0.05) across clusters were age, sex, admission job attachment status, pain intensity, and perceived disability. Given the substantial differences between employed and unemployed claimants further analyses were stratified based on admission job attached status while the other variables were controlled for in multivariable analysis. Intracluster kappa values for the RTW outcome across therapist clusters was small (Kappa = 0.01).
Table 2 presents a descriptive analysis of key claimant characteristics for injured workers who were non-job attached at time of referral to the RTW program (MI group = 125, control group = 74). Claimants were predominately male (80.4%), in their 40 s (average age 43 years), more likely to be single (33.7%) than married (26.1%), have a high school diploma, had an annual income of $69,600 CDN, with a disability duration of 481.8 days, and had moderate levels of pain and disability (mean pain VAS = 5.1/10 and mean Pain Disability Index = 52/70). No statistically significant differences were observed between non-job attached claimants in the MI and control groups on claimant characteristics such as sex, marital status, income, education level, age, disability duration, pain intensity or self-rated disability.
Table 2 Characteristics of non-job attached claimants at referral for return-to-work program
Table 3 presents a descriptive analysis of key claimant characteristics for injured workers who were job attached at the time of referral to the RTW program (MI group = 242, control group = 287). Claimants were predominately male (56.7%), in their 40 s (average age 45 years), more likely to be married (44.6%) than single (27.8%), have a high school diploma, had an annual income of $55,700 CDN, with a disability duration of 140.3 days, and had moderate levels of pain and disability (mean pain VAS = 5.0/10 and mean Pain Disability Index = 47/70). No statistically significant differences were observed between job-attached claimants in the intervention and control groups on claimant characteristics such as sex, marital status, income, education level, age, disability duration, pain intensity or self-rated disability.
Table 3 Characteristics of job attached claimants at referral for return-to-work program
A higher percentage of claimants were observed to be male among claimants who are non-job attached in both the intervention and control groups (78.4 and 83.8%) compared to job attached claimants in the intervention and control groups (60.3 and 53.7%); however this was not statistically significant. Claimants who were non-job attached at program admission in both the intervention and control groups were more likely to be single (36 and 29.7%) while claimants who were job attached at program admission, in both the intervention and control groups, were more likely to be married (43.8 and 45.3%). Common law, divorced, and widowed responses were not considered as a part of the single or married categories. Claimants who were non-job attached at program admission in both the MI and control groups made +$10,000 more annually than claimants who were job attached at program admission despite group membership. High school diploma was the most common education level obtained in the MI and control groups for both non-job attached and job attached claimants. Disability duration was longer among the control groups for job attached and non-job attached claimants (146.2 and 498.6 days) compared to job attached and non-job attached claimants in the intervention groups (135.3 and 471.9 days); however, this was not statistically significant.
Intervention Adherence
Table 4 presents documented MI adherence among intervention clinicians. Clinicians reported completing MI on between 7 and 79% of claimants and session durations lasted between 10 and 50 min. Four target behaviour categories were identified during the study; however RTW accounted for 75% of the target behaviours during the MI sessions. Due to the large difference in adherence rates among intervention clinicians, a sub analysis was completed to evaluate RTW percentages based on level of MI adherence (i.e. comparing the control, MI adherent, and non-adherent groups).
Table 4 Motivational Interviewing (MI) adherence among intervention clinicians
Program Outcomes (Proportion Successfully Returning to Work)
A chi square analysis was used to compare the proportion of successful RTW at program discharge between the intervention and control groups. Successful RTW at program discharge was 12.1% higher for unemployed claimants in the intervention group (intervention group 21.6 vs. 9.5% in control, p = 0.03) and 3.0% higher for job attached claimants compared to the control group (intervention group 97.1 vs. 94.1% in control, p = 0.10) (see Table 5).
Statistically significant differences (p < 0.01) among RTW percentages were found for non-job attached claimants between MI adherent and non-adherent clinicians. The proportion of claimants with successful RTW in the MI adherent intervention group was 33.3%, which was significantly (p < 0.01) higher than the non-adherent intervention group (18.0%) and the control group (9.5%). Successful RTW percentage increased to 47.4% when the MI adherent intervention included RTW as the target behaviour. A statistically significant difference (p = 0.03) was also found among RTW for job attached claimants based on MI adherence, with RTW higher among the MI adherent group (100%) compared to the non-adherent MI group (96.3%) and the control group (94.1%).
Multivariable Logistic Regression
Crude odds ratios (OR) for the intervention variable were 2.64 [95% confidence interval (CI) 1.09–6.41] in unemployed claimants and 2.11 (95% CI 0.86–5.19) in employed claimants. After adjusting for age, sex, annual salary, marital status, pain intensity, disability duration, and perceived disability, the OR for the intervention variable changed to 3.76 (95% CI 1.38–10.25) in unemployed claimants and 2.00 (95% CI 0.77–5.19) in employed claimants. The OR for unemployed claimants reduced to 2.64 (95% CI 0.69–10.14) and increased to 2.50 (95% CI 0.68–9.14) for employed claimants after adjusting for therapist cluster.
Adverse or Unintended Effects
No negative or unintended effects were reported by the clinicians or claimants during the duration of the study. Stakeholders including case managers, physicians, and employers also did not report any adverse effects during the period of the study.