A clinical return-to-work rule for patients with back pain

Abstract

Background: Tools for early identification of workers with back pain who are at high risk of adverse occupational outcome would help concentrate clinical attention on the patients who need it most, while helping reduce unnecessary interventions (and costs) among the others. This study was conducted to develop and validate clinical rules to predict the 2-year work disability status of people consulting for nonspecific back pain in primary care settings.

Methods: This was a 2-year prospective cohort study conducted in 7 primary care settings in the Quebec City area. The study enrolled 1007 workers (participation, 68.4% of potential participants expected to be eligible) aged 18-64 years who consulted for nonspecific back pain associated with at least 1 day's absence from work. The majority (86%) completed 5 telephone interviews documenting a large array of variables. Clinical information was abstracted from the medical files. The outcome measure was "return to work in good health" at 2 years, a variable that combined patients' occupational status, functional limitations and recurrences of work absence. Predictive models of 2-year outcome were developed with a recursive partitioning approach on a 40% random sample of our study subjects, then validated on the rest.

Results: The best predictive model included 7 baseline variables (patient's recovery expectations, radiating pain, previous back surgery, pain intensity, frequent change of position because of back pain, irritability and bad temper, and difficulty sleeping) and was particularly efficient at identifying patients with no adverse occupational outcome (negative predictive value 78%- 94%).

Interpretation: A clinical prediction rule accurately identified a large proportion of workers with back pain consulting in a primary care setting who were at a low risk of an adverse occupational outcome.

Fig. 1: Eligible subjects, refusals and participants in the study. *Eligibility unknown. R = randomization.

Fig. 2: Progress among study participants toward return to work in good health. Note that subjects could not go back into the “failure” group; this category could thus only diminish over time.

Fig. 4: Example of calculations of the measures of validity presented in Table 3.

Fig. 3: Clinical algorithm to predict an outcome at 2 years of return to work in good health (RWGH) among workers consulting in primary care settings for back pain. All values shown are percentages. High-probability categories in each group, as were used to calculate the measures of validity, are circled. Note that the “failure” category includes lack of successful return to work at 2 years of follow-up, either with no attempt to return or despite 1 or more attempts to return to work. CI = confidence interval, Q = question. Q1 is item 15 of the Fear Avoidance Beliefs Questionnaire. Questions 5–7 are from the Roland– Morris Disability Questionnaire: Q5 is item 2; Q6, item 22; and Q7, item 18. Example 1. Mr. Jones answered “Yes” to question 1, “No” to question 3, “7” to question 4 and “No” to question 5. (Notice that because Mr. Jones said “Yes” to question 1, question 2 is not useful.) His estimated probability of success at 2 years in returning to work in good health is 84%. The clinician will reassure him and use a conservative approach. A rapid return to normal activities is the objective. Example 2. Mr. Smith answered “No” to question 1 and “Yes” to question 2. (Questions 3–7 are unnecessary for Mr. Smith.) He thus appears to have a particularly high probability (46%) of failure to return to work in good health by 2 years. The clinician may wish to refer him to a specialized rehabilitation program. Example 3. Mrs. Watson answered “Yes” to question 1, “No” to question 3, “8” to question 4, “Yes” to questions 5 and 6, and “No” to question 7. (Again, question 2 is not needed in Mrs. Watson's case.) Her probability of either success or partial success in returning to work in good health by 2 years is quite high (50% + 45% = 95%). The clinician could ask to see her again and eventually refer her to occupational health services to monitor and improve her work conditions. Keeping the patient at work is the objective.