Background

Pain is a crucial factor that can significantly affect postoperative recovery. However, the knowledge of the relationship between pain and the outcome of benign hysterectomy is incomplete. The intention of this thesis is to expand the existing body of knowledge about the importance of pain in connection with benign hysterectomy and thereby contribute to improving the care and recovery of women who need to undergo this operation.

The overall aim of this thesis was to explore the impact of preoperative pain and pain sensitivity on postoperative recovery, the development of post-surgical pain, and quality of life and health economics after hysterectomy for benign conditions. The specific objectives were 1) to explore associations between preoperative pain thresholds and postoperative recovery, 2) to determine the prevalence of de novo and persistent pelvic pain one year after hysterectomy, and the associated risk factors, and 3) to investigate the association between preoperative pain and recovery of quality of life, and to evaluate the health economics of hysterectomy in relation to the spread of bodily pain preoperatively.

Material and methods

A prospective longitudinal observational cohort multicenter study was conducted at the departments of gynecology and obstetrics at five public hospitals in the southeast of Sweden between 2011 and 2017. A total of 472 women scheduled to undergo abdominal or vaginal hysterectomy for benign conditions were enrolled in the study. Preoperatively, pain thresholds for heat, cold and pressure were assessed by means of quantitative sensory testing and psychometric measures by using the Hospital and Anxiety Depression Scale and the Stress Coping Inventory. The self-reported extent of bodily pain was assessed preoperatively and one year postoperatively using Margolis’s pain drawing instrument. Measures of pain and health-related quality of life were obtained from the Swedish Postoperative Symptom Questionnaire and the EQ-5D-3L and SF-36 forms. A health index measure was derived from the EQ-5D-3L. In addition, clinical data were collected prospectively. To evaluate health economics, a health economic analysis was conducted to compare total costs, quality-adjusted life years (QALYs) and costs per QALY gained as a measure of the average cost-effectiveness ratio (ACER).

Results

A high temperature for pain threshold for cold, i.e., a low cold pain threshold, was significantly associated with high postoperative maximum pain intensity and a high sum score of postoperative symptoms. Low cold and heat pain thresholds were both significantly associated with higher consumption of non-opioid analgesics.

Four subgroups of patients could be identified from the preoperative Margolis pain drawing: women with no pain, pelvic pain only, pain in the pelvis and other areas, and pain in non-pelvic areas only. The incidence of de novo pelvic pain and persistent pelvic pain after one year was 6.2% and 16.4 %, respectively. De novo pelvic pain developed only in women with preoperative pain in non-pelvic areas. Risk factors for de novo pelvic pain were a long hospital stay, a preoperative high number of pain areas on the pain map, anxiety, high preoperative pain intensity, and a low self-rated quality of life. The risk factors for persistent pelvic pain were similar: a higher number of pain areas, a higher frequency of preoperative pain but also younger age. Although the health index after one year increased overall in all the four subgroups, and women with pelvic pain improved the most in the health index, this group still scored the lowest both preoperatively and one year after hysterectomy. The recovery trajectory in health indices differed significantly between the four subgroups with women with pain in the pelvis and in other areas having the worst recovery trajectory. This group therefore also showed the significantly lowest value of QALYs gained. Health economically, the same group showed the highest total costs and consequently the highest ACER compared to the other three subgroups.

Conclusions

Pain thresholds for cold seemed to predict postoperative pain intensity and symptoms of discomfort. The effect of applying the measurement of pain thresholds in clinical practice is unclear and requires further study.

Although hysterectomy appeared to be reasonably effective in curing women with pelvic pain a non-negligible proportion of women developed de novo pelvic pain or had persistent pelvic pain. De novo pelvic pain appeared to develop only in women who preoperatively had widespread pain in non-pelvic areas. Risk factors for de novo and persistent pelvic pain could be identified. Several preoperative pain-related measures were joint risk factors for de novo and persistent pelvic pain.

The preoperative extent of bodily pain appeared to affect recovery after hysterectomy significantly and, from a health economically societal perspective, the extent of preoperative bodily pain seemed to be a cost-driving factor in benign hysterectomy.