Safe Analgesic Use in Patients With Renal Dysfunction
The ubiquity of chronic pain conditions and associated disability impair the quality of life of many patients, prompting initiatives to make pain management a priority. However, effective pain management can sometimes be undermined when clinicians are uncomfortable with treatment strategies for patients with significant medical comorbidities. Among these, clinicians are likely to be particularly unfamiliar with the appropriate use of analgesics and co-analgesic adjuvants in the treatment of patients with pain and co-existing renal insufficiency (RI), i.e., suboptimal renal function and end-stage renal disease (ESRD).
It is likely that clinicians will encounter pain management needs among patients with RI. Chronic kidney disease (CKD) is highly prevalent; estimated to affect over 19 million people in the United States.1 Based upon trends in the growth of the aging sector of the population, as well as rates of hypertension and diabetes mellitus, it is anticipated that rates of renal dysfunction in the general population will continue to rise.2 Elderly patients, i.e., those over age 65 years, constitute the majority of patients on dialysis and are the fastest growing cohort in end-stage renal disease.3
In addition, pain constitutes a significant symptom accompanying renal dysfunction interfering with adaptive functioning and quality of life. Patients with CKD are specifically at risk for pain, and available evidence suggests that such patients are especially vulnerable to ineffective pain management.4-7 A prospective chart review of dialysis patients revealed that 50% reported problems with pain.5 The most common pain complaints encountered suggested a musculoskeletal etiology, e.g., osteoarthritis, muscle cramps, inflammatory arthritis, and osteomyelitis. Metabolic bone disease accompanying renal dysfunction can produce pain associated with moderate-to-severe bone pain, e.g., carpal-tunnel syndrome, arthralgias, fractures, and bone cysts. Other common pain-related conditions were related to the dialysis procedure directly, peripheral vascular disease, trauma, or malignancy.5 Restless legs syndrome (RLS) contributed significantly to the morbidity of pre-dialysis CKD patients8 as well as among dialysis-dependent patients.9 Because of advanced age, many patients with CKD have other medical comorbidities that contribute to the experience of chronic pain, e.g., diabetes mellitus, giving rise to kidney disease, can likewise predispose patients to painful polyneuropathies.
Both the co-occurrence of pain and renal disorders and the trend toward increasing rates of RI in the general population invite the need for familiarity with the safety, pharmacokinetic profile, and efficacy of analgesics and adjuvants in individuals with RI. Unfortunately, the evidentiary base informing the selection, dosing, and monitoring of analgesic and co-analgesic adjuvant agents in RI is limited. There is a dearth of literature on effective analgesic use in patients with renal dysfunction. Additionally, studies of the use of such agents in patients with renal impairment are often confined to a few participants for each medication. Despite the lack of extensive empiric investigation, attempts are made in this paper to provide a pragmatic review of analgesic pharmacologic approaches in the context of RI.