Weight reduction, improving leg strength, and taking a global approach to the treatment of pain in general may reduce the prevalence and incidence of foot pain in older, community-dwelling adults, according to results of a large, longitudinal observation study presented at the 2015 Osteoarthritis Research Society International (OARSI) World Congress.
“Weight, poorer leg strength, and pain at other sites than the feet are consistently associated with prevalent foot pain and predict new foot pain,” stated lead investigator Laura Laslett, PhD, Menzies Research Institute, University of Tasmania, Hobart, Tasmania, Australia, speaking here on May 2. “Poor psychological well being is associated with existing foot pain,” she added.
Foot pain is common, and is associated with a decreased ability to undertake activities of daily living, problems with balance and gait, and increased risk of falls.
Dr. Laslett and colleagues assessed the non-structural factors associated with foot pain cross-sectionally and longitudinally over 5 years in a community-dwelling sample of 1,037 older (50 to 80 years of age) adults. The researchers excluded patients who were being institutionalised and those with contraindication for magnetic resonance imaging.
The team assessed all participants concerning foot pain (yes or no) at baseline and 5 years later. Information on potential correlates came from demographic factors (age, sex, cigarette smoking);
diabetes; anthropometry (objectively measured weight, body mass index [BMI], waist-to-hip ratio); lower-leg strength (kg) measured using a dynamometer; leg lean mass (kg) from dual-emission X-ray absorptiometry; leg-muscle quality determined as leg strength ÷ leg lean mass; steps per day recorded by a pedometer; joint pain in the neck, shoulder, back, hands, hips, and knees; the Psychological Well being scale of Assessment of Quality of Life (AQoL) questionnaire; and serum vitamin D determination.
The 1,037 subjects were aged 50 to 80 years (mean age: 63 years), and were 51% female. At baseline, the mean BMI was 27.8 kg/m2. Also at baseline, 680 subjects had no foot pain and 412 did have foot pain. During the next 5 years, new foot pain developed in 97 subjects. Prevalence of foot pain at baseline was 37.7% (95% confidence interval [CI], 34.8% to 40.6%).
Compared with subjects who had no foot pain at baseline, subjects with current pain were more likely to report diabetes (5.1% vs 8.3%; P = .04), have a greater amount of measurable fat mass (BMI 27.3 vs 28.9 kg/m2; P < .001), walk fewer steps per day (9,749 vs 8,968 steps/day), report pain at more joints other than the feet (2.2 vs 3.8 sites; P < .001), and have poorer scores on the well being scale (2 vs 3; P < .001).
After adjusting for age, sex, and diabetes, baseline foot pain was associated with weight (odds ratio [OR], 1.02; 95% CI, 1.01 to 1.03; P < .001), leg strength (OR, 0.99; 95% CI, 0.99 to 0.999; P = .023), pain at 3 sites (OR, 2.26; 95% CI, 1.29 to 3.95; P = .004), pain at 4 sites (OR, 3.49; 95% CI 2.00 to 6.09; P < .001), pain at 5 sites (OR, 5.09; 95% CI, 2.84 to 9.12; P < .001), pain at 6 sites (OR, 11.14; 95% CI, 5.66 to 21.91; P < .001), and well being scores (OR, 1.22; 95% CI, 1.11 to 1.35; P < .001).
The incidence of new (prevalent) pain after 5 years was 34% (95% CI, 31% to 38%). New foot pain at 5 years was significantly associated with pain at 3 sites (OR, 2.58; 95% CI, 1.13 to 5.9; P = .025) and 5 sites (OR, 2.95; 95% CI, 1.13 to 7.73; P = .023).
New foot pain was associated with male gender and the following at baseline: greater BMI and hip circumference, poorer leg-muscle quality, poorer psychological well being, and pain at more sites other than the feet (P < .05 for all). As a point of comparison, psychological well being was not an independent predictor of new knee pain after 5 years (OR, 1.06; 95% CI, 0.90 to 1.26; P = .47).