Abstract
BackgroundPain persists in a moderate number of patients following hip or knee replacement surgery. Persistent pain may subsequently lead to the prolonged consumption of analgesics after surgery and expose patients to the adverse drug events of opioids and NSAIDs, especially in older patients and patients with comorbidities. This study aimed to identify risk factors for the increased use of opioids and other analgesics 1 year after surgery and focused on comorbidities and surgery-related factors.MethodsAll patients who underwent a primary hip or knee replacement for osteoarthritis from 2002 to 2013 were identified. Redeemed prescriptions for acetaminophen, non-steroidal anti-inflammatory drugs (NSAIDs), and opioids (mild and strong) were collected from a nationwide Drug Prescription Register. The user rates of analgesics and the adjusted risks ratios for analgesic use 1 year after joint replacement were calculated.ResultsOf the 6238 hip replacement and 7501 knee replacement recipients, 3591 (26.1%) were still using analgesics 1 year after surgery. Significant predictors of overall analgesic use (acetaminophen, NSAID, or opioid) were (risk ratio (95% CI)) age 65–74.9 years (reference < 65), 1.1 (1.03–1.2); age > 75 years, 1.2 (1.1–1.3); female gender, 1.2 (1.1–1.3); BMI 30–34.9 kg/m2 (reference < 25 kg/m2), 1.1 (1.04–1.2); BMI > 35 kg/m2, 1.4 (1.3–1.6); and a higher number of comorbidities (according to the modified Charlson Comorbidity Index score), 1.2 (1.1–1.4). Diabetes and other comorbidities were not significant independent predictors. Of the other clinical factors, the preoperative use of analgesics, 2.6 (2.5–2.8), and knee surgery, 1.2 (1.1–1.3), predicted the use of analgesics, whereas simultaneous bilateral knee replacement (compared to unilateral procedure) was a protective factor, 0.86 (0.77–0.96). Opioid use was associated with obesity, higher CCI score, epilepsy, knee vs hip surgery, unilateral vs bilateral knee operation, total vs unicompartmental knee replacement, and the preoperative use of analgesics/opioids.ConclusionsObesity (especially BMI > 35 kg/m2) and the preoperative use of analgesics were the strongest predictors of an increased postoperative use of analgesics. It is remarkable that also older age and higher number of comorbidities predicted analgesic use despite these patients being the most vulnerable to adverse drug events.
Highlights
Hip and knee replacement are performed to reduce pain and regain function in patients with late-stage arthritis [1, 2], 10–20% of patients continue to suffer from persistent pain after surgery [3, 4]
Only a limited number of large-scale studies have been conducted on the trajectories of analgesic consumption and the risk factors associated with increased analgesic consumption after surgery [9,10,11,12,13,14,15,16,17,18,19,20,21], even though the risks for adverse events of opioids and non-steroidal anti-inflammatory drugs increase in long-term use [22,23,24], especially in elderly patients with comorbidities
The proportion of patients who redeemed at least one type of analgesic drug decreased to 26.1%, and Non-steroidal anti-inflammatory drug (NSAID) were still the most common (15.5%), followed by acetaminophen (10.1%), and opioids (6.7%)
Summary
Hip and knee replacement are performed to reduce pain and regain function in patients with late-stage arthritis [1, 2], 10–20% of patients continue to suffer from persistent pain after surgery [3, 4]. High levels of preoperative pain, knee surgery (compared to hip surgery), and younger age have all been associated with an increased overall consumption of analgesic drugs [9]. Obesity, female gender, younger age, and depression are associated with an increased consumption of NSAIDs [18,19,20] General comorbidities, such as diabetes, a risk factor for persistent pain, have only been analyzed in one previous study [9], in which no differences in overall analgesic consumption after knee replacement were reported. Persistent pain may subsequently lead to the prolonged consumption of analgesics after surgery and expose patients to the adverse drug events of opioids and NSAIDs, especially in older patients and patients with comorbidities. This study aimed to identify risk factors for the increased use of opioids and other analgesics 1 year after surgery and focused on comorbidities and surgery-related factors
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