Incidence rate of chronic pain after 1.5–2 years of thoracotomy between paravertebral block versus epidural block: a cohort study

Paravertebral block and epidural block are frequently employed for post-thoracotomy pain relief. It is not clear which postoperative analgesia method is effective for the chronic pain after the postoperative long term progress. Our hypothesis was that paravertebral block would be more effective than epidural block for chronic pain 1.5–2 years after thoracotomy. A cohort study investigating postoperative pain was performed in lung cancer patients undergoing thoracotomy between the ages of 20–80 year-old, employed for another randomized controlled trial. In previously study, the patients were randomly allocated into either the epidural block or paravertebral block group (n = 36/group). Patients in each group received the respective block placement with continuous 0.2% ropivacaine infusion at 5 ml/h. The patients completed a telephone observational survey using the EQ-5D-5L at 1.5–2 years. Forty-eight patients, 23 in the epidural block group and 25 in the paravertebral block group, were included in the final analysis. Quality of life scores at 1.5–2 postoperative years was similar in both groups. Mean scores ± standard deviation and 95% confidence interval were 0.899 ± 0.081 (0.705–0.938) in the epidural block group and 0.905 ± 0.079 (0.713–0.938) in the paravertebral block group, respectively, p = 0.81. The incidence rate of chronic postsurgical pain was eight patients; four in the epidural block group (17.4%) and four in the paravertebral block group (16.0%). There was no difference in incidence rate of long-term chronic postsurgical pain at 1.5–2 years after thoracotomy between the both groups. Our result will be used for further study protocols.