Effects of Hypovitaminosis D on Preoperative Pain Threshold and Perioperative Opioid Use in Colorectal Cancer Surgery: A Cohort Study.

Background: Postoperative pain after colorectal cancer surgery has a significant impact on postoperative physical and mental health. Vitamin D deficiency has been correlated with both acute pain states, including postoperative and post-traumatic pain, and several chronic pain diseases. The effects of hypovitaminosis D on preoperative pain threshold and perioperative opioid use in colorectal cancer surgery still need to be studied.

Objectives: To find the relationship between hypovitaminosis D on pain threshold, perioperative opioid use, and postoperative complications in colorectal cancer surgery.

Study Design: A total of 112 patients, who were enrolled in this prospective, observational trial, were divided into 2 groups based on their preoperative serum 25-hydroxyvitamin D (25 [OH] D3) levels: (1) group D: vitamin D-deficient group (< 20 ng/mL); and (2) group S: vitamin D-sufficient group (>= 20 ng/mL).

Methods: Primary outcomes were pain threshold indexes, perioperative dosages of opioid use, and postoperative pain. Secondary outcomes were other postoperative complications.

Results: Preoperative serum level of vitamin D was 14.94 ± 3.10 ng/mL in group D and 24.20 ± 4.80 ng/mL in group S. Significant differences were showed in the 3 indexes of pain threshold and analgesic consumption between the 2 groups (P < 0.05). A low 25 (OH) D3 level was associated with a higher opioid dose of sufentanil. There was an association between 25 (OH) D3 and pain enduring threshold (PET), beta coefficient beta = 0.532, 95% confidential interval  (0.440, 0.623), P < 0.001. The history of diabetes mellitus (DM) and vitamin C and vitamin D levels may be risk factors of surgical site infections (SSI), and the binary logistics regression model is statistically significant, chi-squared = 35.028, P < 0.001.

Limitations: There is room for further expansion in the sample size. Our study lacked objective indicators to measure pain threshold. Intestinal recovery time and total hospital stay were not included in the final analysis. In the follow-up study, the vitamin D supplementation group should be set and the specific site of colorectal cancer surgery also needs to be divided more carefully.

Conclusions: On the basis of the study results, hypovitaminosis D is associated with increased perioperative opioid consumption in colorectal cancer surgery. Sensory perception and pain threshold of patients with insufficient 25 (OH) D3 concentration were more sensitive, and PET was lower. History of DM, vitamin D, and vitamin C may be factors related with SSI. Future studies are needed to investigate their relationship further and discover if postoperative pain and pain threshold can benefit from vitamin D supplementation in these patients.