Workers’ mental health comorbidities such as anxiety and depression are correlated with lower levels of functional recovery from back pain than physical health comorbidities, according to new research.

The Workers Compensation Research Institute (WCRI) study, “Comorbidities and Recovery after Physical Therapy for Low Back Pain,” based on a large sample of 68,850 workers who received physical therapy for low back pain, examined the prevalence of self-reported comorbidities and their association with functional improvements. The study also looked at other important predictors of physical therapy outcomes.

Comorbidities are medical conditions that workers who sustain work-related injuries may have in addition to their work injuries.

According to the WCRI study, there has been a lack of information regarding the prevalence of comorbidities among injured workers. They are rarely covered under workers compensation and therefore underreported in workers comp claims data.

“Identifying these comorbidities and understanding their impact on recovery may help workers compensation stakeholders better understand which low back pain cases are more likely to have poorer outcomes and potentially adapt treatments for workers with high-risk comorbidities,” said Ramona Tanabe, president and CEO of WCRI.

According to the study, the most common self-reported mental health comorbidities among workers compensation patients were sleep dysfunction (17 percent), depression (16 percent), and anxiety or panic disorders (also 16 percent). Physical comorbidities commonly reported were hypertension (28 percent) and arthritis (21 percent). In addition, physical conditions such as diabetes, lung conditions, gastrointestinal disease and severe obesity were reported by 9-11 percent of patients studied.

Reduced functional improvements were most often associated with sleep dysfunction, severe obesity and kidney disease.

The key measure of functional improvement used for the research is a functional status (FS) score, which ranges between 0 and 100. A larger FS score change between intake and discharge represents greater improvement in function.

In addition to FS scores, other outcome variables evaluated by the researchers included whether the workers receiving therapy for back pain experienced “minimal clinically important improvement” and whether they had “very limited” function at discharge.

According to the researchers, the FS score change was 13.7 points in workers reporting mental health comorbidities alone, while it was 14.8 points for those workers reporting only physical comorbidities.

The researchers conclude that better engagement, assessment and treatment of associated mental health comorbid conditions could potentially improve functional outcomes of physical therapy (and other treatments) of low back pain, supporting the idea with reference to past studies, which have suggested that early assessments and interventions related to behavioral health issues are associated with better return-to-work outcomes.

Still, the researchers repeatedly note that routine screening, assessment and treatment of conditions like sleep dysfunction would be challenging to implement in the workers comp system at large, also conceding that future study is needed to gauge the potential impact of treatments. They also acknowledge in the concluding remarks of the report that the idea of providing workers comp coverage for sleep medications, studies and appliances, or for weight loss treatments, would spark a good deal of debate.

“Even if it is not practical for comorbidities to be treated during the course of the work injury,… information about comorbidities can be of prognostic value in helping to make decisions about resource allocation and time to discharge from physical therapy care,” the report notes.

In addition to comorbidities, the researchers looked at other factors impacting FS score changes, including the timeliness of providing physical therapy services, functional status prior to therapy, initial pain intensity, and the age of workers involved.

Regarding timeliness, the study found that if physical therapy for low back pain was delayed, a poorer outcome could be expected that correlates with an increase in workers compensation costs. In fact, the timeliness of the provision of physical therapy was more strongly related to improved outcomes than comorbidities, the report notes.

FS score changes also decreased with increasing age. The change for workers over 55 was 26-28 percent smaller than for those under age 25.

The results are based on data prospectively collected by Focus on Therapeutic Outcomes (FOTO) from low back pain patients at their first and last physical therapy visit over the 2017-2021 period. The data included information on patient-reported functional outcomes, patient-level socio-demographics, self-reported comorbidities as well as other characteristics.

The authors of the study are Vennela Thumula, Te-Chun Liu and Randall D. Lea.

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