PURPOSE

The iMTA productivity cost questionnaire (iPCQ) has been recommended as a measurement tool for productivity cost, however, its use in routine care is hindered by the length of this questionnaire (18 questions). This study developed and tested a short-form (SF-) iPCQ.

METHOD

A secondary analysis of the Groningen Spine Cohort's baseline data from patients with low back pain referred for tertiary care was performed. Six SFs were evaluated against the comprehensive iPCQ. Spearman correlation (r), intraclass correlation coefficient (ICC, agreement), standard error of measurement (SEM), and Bland-Altman's plot tested the congruence of the SFs with the comprehensive iPCQ.

RESULTS

The sample consisted of 1220 patients with low back pain. The SF version with the highest correlation (SF-3; 7 items) with the comprehensive iPCQ had r = 0.99, ICC = 0.99, SEM = 295, while the SF with the least number of items (SF-6; 5 items) had r = 0.84, ICC = 0.91, SEM = 2063. The mean productivity cost estimates of SF-3 and SF-6 were €3414 (95% CI: 3036-3791) and €3333 (95% CI: 2970-3696) respectively while that for the comprehensive iPCQ amounted to €3456 (95% CI: 3189-3720).

CONCLUSION

A SF with seven questions was developed with a high agreement with the comprehensive iPCQ. Initial clinimetric testing was satisfactory. Further assessment is recommended.