Are Older Adults Missing From Low Back Pain Clinical Trials? A Systematic Review and Meta-Analysis TATJANA PAECK, MANUELA L. FERREIRA, CLIVE SUN, CHUNG-WEI CHRISTINE LIN, ANNE TIEDEMANN, AND CHRIS G. MAHER Objective. There is evidence to suggest that older adults are underrepresented in randomized controlled trials of health interventions. The aim of this review was to systematically examine the age-related inclusion criteria distribution of participants in randomized controlled trials (RCTs) of low back pain (LBP) interventions and to investigate if this distribution pattern changes over time. Methods. We identified, in PubMed, 1,047 RCTs on nonspecific LBP published since 1992, of which a random sample of 400 was assessed for inclusion in the review. Included studies were grouped according to treatment type. Data were extracted on year of publication, types of treatment, total number of participants, age inclusion criteria, and age of included participants. Results. A total of 274 RCTs published between 1992 and 2010 met the inclusion criteria. A total of 41.6% (n  114) of the included trials excluded people ages >65 years. The pooled mean age of participants was 44.3 years (95% confidence interval 42.4 – 46.3); the pooled minimum age for inclusion was 19.8 years and the pooled maximum age for inclusion was 65.4 years. We found no trend of including older participants in RCTs on LBP over time. Conclusion. Despite an aging population around the globe, older adults are largely excluded from RCTs evaluating management of LBP, and there is no evidence of change in this practice over the last 2 decades. INTRODUCTION Low back pain (LBP) is a common and costly condition. A recent systematic review of the prevalence of LBP esti- mated its point prevalence to be approximately 12%, with a 1-month prevalence of 23% (1). The review also demon- strated that this condition is more common in women and those ages 40 – 80 years. LBP is currently ranked the num- ber one cause of years lived with disability in the world and number 6 in terms of disability-adjusted life-years (2). The costs associated with LBP are substantial; for example, Australia spends in excess of $1 billion each year on direct costs and $8 billion on indirect costs (3). While it is clear that LBP affects men and women of all ages, it was previously believed that adults of working age were the most vulnerable (4 – 6). However, Dionne et al (7) recently ascertained that even though the prevalence of benign back pain indeed appears to decrease with increas- ing age, the prevalence of severe back pain continues to increase. Moreover, LBP is the third most commonly re- ported musculoskeletal condition among older patients visiting primary care in the US (6) and the third leading cause of chronic disability in people ages 65 years in Canada (8). These data indicate that LBP is a significant health condition in older adults as well. Outside the LBP field, there is compelling evidence suggesting that older adults are significantly underrepresented in randomized controlled trials (RCTs) of health interventions, despite their higher levels of morbidity, greater consumption of prescription medications, cognitive impairment, attitudi- nal barriers, and greatest potential for clinical benefit com- pared to younger subjects (9,10). For example, a systematic review by Levy and colleagues revealed that 53% of the identified clinical trials excluded people ages 65 years and the exclusion percentage increased to 72% for those ages 75 years (11). While this issue has not been directly Drs. Lin and Tiedemann’s work was supported by the National Health and Medical Research Council of Australia. Dr. Maher’s work was supported by the Australia Research Council. Tatjana Paeck, BA, Manuela L. Ferreira, PhD, Clive Sun, MBBS, Chung-Wei Christine Lin, PhD, Anne Tiedemann, PhD, Chris G. Maher, PhD: The George Institute for Global Health, Sydney Medical School, University of Sydney, Syd- ney, New South Wales, Australia. Address correspondence to Manuela L. Ferreira, PhD, The George Institute for Global Health, PO Box M201, Mis- senden Road, Sydney, New South Wales 2050, Australia. E-mail: mferreira@georgeinstitute.org.au. Submitted for publication May 16, 2013; accepted in re- vised form December 3, 2013. Arthritis Care & Research Vol. 66, No. 8, August 2014, pp 1220 –1226 DOI 10.1002/acr.22261 © 2014, American College of Rheumatology ORIGINAL ARTICLE 1220