Association of Statin Use with Risk of Back Disorder Diagnoses

This week from Dr. Cerami and Utah Sports and Wellness

From: Journal of the American Medical Association Internal Medicine, 2017

Quick Summary:

Back pain results in tremendous disability and cost; therefore, understanding predisposing or protective factors deserves attention. Statins are widely used, but there is no consensus on whether statins are protective of or deleterious to musculoskeletal conditions.  Because statins may increase vulnerability to myalgias and contribute to the myopathic component often experienced with back pain, the objective of this study was to examine the association of statin use with the risk of back disorder diagnoses. In this study, statin use had a 27% higher likelihood of back disorders. Statin use was  also found to be associated with increased likelihood of back disorder diagnoses and a dose response to both dosage and duration.

Abstract:

We retrieved health care data for patients enrolled in TRICARE, the health insurance system of the US Department of Defense, in the San Antonio military area from October 1, 2003, to March 1, 2012.5 Inclusion criteria were being older than 30 years and having at least 1 medical encounter during the baseline period (2 years before the index date) and the follow-up period (starting 90 days after the index date through March 1, 2012, except for nonusers who were subsequently prescribed statins and for whom follow-up was censored at the date they filled their statin prescription). Two treatment groups were identified: (1) statin users who recently received a first-time prescription for a statin and continued its use for 120 days or more and (2) statin nonusers who never used statins as well as statin users prior to being prescribed statins.5 Prevalent statin users were excluded. This study was approved by the institutional review boards of Brooke Army Medical Center and the VA North Texas Health System. Patient informed consent was waived by both institutional review boards because the data were deidentified before being forwarded to the investigators. Data analyses were performed between February 23, 2016, and August 8, 2016. Our outcome was an occurrence of disease category 205 for back disorders (eg, spondylosis, intervertebral disc disorders, and other back problems), as listed in the Agency for Healthcare Research and Quality’s Clinical Classifications Software (based on the International Classification of Diseases, Ninth Revision, Clinical Modification codes). We created a PS using 115 baseline characteristics and matched treatment groups in a 1:1 ratio for the nearest neighbor (caliper of 0.01).5 Primary analyses used conditional logistic regression analysis to examine the odds ratio (OR) of outcomes in the PS-matched cohort. We also calculated the number needed to harm. Secondary analyses examined the OR of outcomes in the overall cohort (all patients identified before PS matching) and in several prespecified cohorts. Baseline characteristics for treatment groups were examined using χ2 test to compare categorical variables and 2-tailed t test for continuous variables. Standardized differences were also calculated. Comparisons of outcomes, using conditional logistic regression, were considered statistically significant at P < .05. Statistical analyses were performed using SPSS software version 23 (IBM). The overall cohort included 60 455 patients, of whom 28 831 (47.7%) were men and 31 624 (52.3%) were women with a mean (SD) age of 46.6 (12.2) years. TRICARE beneficiaries include approximately 17% active duty military, their families, and veterans. We matched 6728 statin users with 6728 nonusers, and selected baseline characteristics are listed in Table 1. Statin users took statins for a median (interquartile range [IQR]) of 3.7 (1.9-4.9) years. Among statin users, 425 935 prescriptions (72%) were for simvastatin. Statin users in the PS-matched cohort had a higher likelihood of back disorders (OR, 1.27; 95% CI, 1.19-1.36). The number needed to be exposed for an additional harm was 17.6 All secondary analyses showed similar results, including analyses of longer use and higher intensity of statin

These authors also note:

• “Back pain results in tremendous disability and cost.”
•  “Few studies have examined the association of statins with back pain.”
• Previous studies have indicated an increased risk of arthropathies and back pain in patients taking statin drugs.