Background: In groin hernia repair studies, chronic pain is a frequently used primary endpoint. However, its impact on daily life activities has been less investigated. Such an outcome is relevant for the patient and surgeon and cannot be extrapolated out of pain scores. The Pain Disability Index (PDI), a questionnaire wherein patients rate their impairment, could reveal the consequences of pain. The PDI was therefore introduced in a trial upon open mesh-based inguinal hernia repair.
Methods: A total of 172 patients received an open preperitoneal repair or Lichtenstein procedure. Primary endpoints for this report were the PDI scores measured preoperatively, after 2 weeks and 3 months. The Visual Analogue Scale pain (VAS) scores were assessed simultaneously. Chronic pain was defined as any VAS score at 3 months postoperatively.
Results: The PDI scores of all measure moments were available for 146 patients (85%). A correlation between the PDI and VAS score was found at all moments (P<0.001). A total of 47 patients reported chronic pain. The intensity of their pain correlated more significantly with the PDI than VAS scores at 2 weeks postoperatively (R=0.286, P<0.001 vs. R=0.175, P=0.036). Thirty chronic pain patients reported restrictions. The main disabilities were for the recreation, occupation and sexual subscale. Their PDI scores were not influenced whether work was rated as light or heavy (P=0.570). Twelve patients without chronic pain reported impairment in daily life (mean PDI score 8.8+/-10.8).
Conclusion: The PDI is feasible in inguinal hernia repair and can be used as an adjuvant in pain measurement. It can identify patients still suffering postoperatively who might otherwise be missed. Furthermore, the PDI could serve as a predictor for chronic pain.