Researchers at Boston Medical Centre found that frequent, persistent back pain is associated with earlier death in a study of more than 8,000 older women who were followed for an average of 14 years. After controlling for important socio-demographic and health factors, women who reported frequent, persistent back pain had a 24% increased risk of death compared to women with no back pain.
The study is the first to measure the impact of back pain persisting over time on mortality. The researchers also found that disability measured after back pain helped explain the association.
Back pain is the leading cause of disability worldwide, and women aged 40-80 years have the highest prevalence of back pain. Also, women report more frequent and debilitating back pain compared to men. The proportion of adults over the age of 65 is increasing rapidly in the US, and optimising physical health in order to extend life for older adults is a well-documented public health goal.
“To our knowledge, our study is the first to measure disability after measurement of back pain. This allowed for a prospective analysis of back pain that persisted over time and later rates of disability, which may help explain the association between back pain and mortality,” said Dr Eric Roseen, a research fellow at Boston Medical Centre and leading author of the study. “Our findings raise the question of whether better management of back pain across the lifespan could prevent disability, improve quality of life, and ultimately extend life.”
After taking baseline measurements of back pain, researchers followed up with participants two years later and measured back pain again. In year four, participants were asked about and observed doing common activities of daily living. The study found that disability following the measurements of back pain explained much of the association with mortality.
Specifically, difficulty performing one or more basic daily activities, like walking short distances or meal preparation, explained nearly half (47%) of the effect of frequent persistent back pain on mortality. Slow performance on more objective measures, like observed walking speed or repetitive standing up from a chair, each explained about a fourth of this association (27% and 24%, respectively). Of 8,321 women in the study, 56% died over a median follow up of 14.1 years. A higher proportion of women with frequent persistent back pain died (65.8%) than those with no back pain (53.5%).
While the study’s findings are consistent with prior studies that found older women with daily or disabling back pain had elevated mortality risk, why this association occurs remains unclear.
“Back pain may directly impair daily activities, but older adults could inappropriately avoid them due to fear of re-injury or worsening of symptoms. Being unable to perform, or avoiding, daily activities could lead to weight gain, development or progression of other chronic health conditions, and ultimately earlier death,” said Roseen.
These results lay the foundation for future studies to assess the long-term impact of back pain treatments and self-care strategies. Clinicians should assess physical function in older adults with back pain and recommend guideline-based management, which encourages use of less invasive treatments.
Background: The impact of back pain on disability in older women is well-understood, but the influence of back pain on mortality is unclear.
Objective: To examine whether back pain was associated with all-cause and cause-specific mortality in older women and mediation of this association by disability.
Design: Prospective cohort study.
Setting: The Study of Osteoporotic Fractures.
Women aged 65 or older.
Measurement: Our primary outcome, time to death, was assessed using all-cause and cause-specific adjusted Cox models. We used a four-category back pain exposure (no back pain, non-persistent, infrequent persistent, or frequent persistent back pain) that combined back pain frequency and persistence across baseline (1986–1988) and first follow-up (1989–1990) interviews. Disability measures (limitations of instrumental activities of daily living [IADL], slow chair stand time, and slow walking speed) from 1991 were considered a priori potential mediators.
Results: Of 8321 women (mean age 71.5, SD = 5.1), 4975 (56%) died over a median follow-up of 14.1 years. A higher proportion of women with frequent persistent back pain died (65.8%) than those with no back pain (53.5%). In the fully adjusted model, women with frequent persistent back pain had higher hazard of all-cause (hazard ratio [HR] = 1.24 [95% CI, 1.11–1.39]), cardiovascular (HR = 1.34 [CI, 1.12–1.62]), and cancer (HR = 1.33, [CI 1.03–1.71]) mortality. No association with mortality was observed for other back pain categories. In mediation analyses, IADL limitations explained 47% of the effect of persistent frequent back pain on all-cause mortality, slow chair stand time, and walking speed, explained 27% and 24% (all significant, p < 0.001), respectively.
Limitations: Only white women were included.
Conclusion: Frequent persistent back pain was associated with increased mortality in older women. Much of this association was mediated by disability.
Eric J Roseen, Michael P LaValley, Shanshan Li, Robert B Saper, David T Felson, Lisa Fredman