Serum Potassium as a Predictor of Clinical Outcomes in an Older Patient Cohort With Chronic Postsurgical Pain

Serum Potassium as a Predictor of Clinical Outcomes in an Older Patient Cohort With Chronic Postsurgical Pain: Retrospective Analysis of A Multi-Center Prospective Database in China

Perioperative serum potassium in patients over 65 impacts recovery, quality of life and physical functioning. While perioperative serum potassium is an important preoperative risk factor for poor surgical outcomes in older adults, the relationship between perioperative serum potassium and postsurgical pain in this population has not been investigated. The investigators hypothesized that preoperative serum potassium would be associated with greater odds of postsurgical chronic pain.

This study is a secondary interim analysis of 'Perioperative Database of Chinese Elderly Patients,' an ongoing prospective observational cohort study that began in 2020 at the muti-center in China with the primary aim of complications in older adults before and after surgery. The investigators described the demographics, comorbidities, and assessment scores as n (percentage) or mean (SD), as appropriate. Unadjusted bivariate analyses included t-test or χ2 test to compare differences between minimal pain and intrusive pain at 3 months after surgery based on demographics, preoperative status, baseline pain status and perioperative serum potassium. The investigators then created a logistic regression model with the outcome of persistent pain at 3 months after surgery and serum potassiumas the main predictor, adjusting for baseline pain, surgery type and surgery part and frailty status based on the hypothesis and association. The investigators also tested for the interaction between baseline pain and serum potassiumas.

Inclusion Criteria:

• Geriatric surgical patients ≥65 years old
• Diagnosis of Chronic postsurgical pain (CPSP) CPSP was made based on the guidelines of the International Society for Pain (CPSP: ICD-11) as follows: Chronic postsurgical pain is chronic pain developing or increasing in intensity after a surgical procedure and persisting beyond the healing process, i.e. at least 3 months after surgery. The pain is either localised to the surgical field, projected to the innervation territory of a nerve situated in this area, or referred to a dermatome (after surgery/injury to deep somatic or visceral tissues). Other causes of pain including infection, malignancy etc. need to be excluded as well as pain continuing from a pre-existing pain problem. Dependent on type of surgery, chronic postsurgical pain often may be neuropathic pain.

Exclusion Criteria:

• Patients in the central nervous system group were excluded from cardiac and neurosurgery, patients in the heart injury group were excluded from cardiac surgery.
• patients who did not agree to participate in the study were excluded in all groups.