Abstract
BACKGROUND: To describe the societal costs during one year of follow-up among older adults seeking chiropractic care due to a new episode of low back pain (LBP), and to determine what factors predict high societal costs in this population. METHODS: Prospective cohort study, within chiropractic private practices (n = 38) in the Netherlands. 223 people ≥ 55 years of age with a new episode of LBP seeking chiropractic care participated. The primary outcome was total societal costs. High societal costs were defined as patients with costs in the top 20th percentile. The final prediction models were obtained using forward selection. Results were presented for the total population and stratified for retirement status. The model's prognostic accuracy (Hosmer-Lemeshow X(2), Nagelkerke's R(2)) and discriminative ability [area under the receiver operating curve (AUC)] were assessed, and the models were internally validated using bootstrapping. RESULTS: The mean total annual societal cost per patient was €5297 [95% confidence interval (CI): 4191-6403]. The biggest cost driver was presenteeism (65% of total costs), and costs were higher among non-retired participants (€7759; 95% CI 6047-9470) than retired participants (€1892; 95% CI 1088-2695). In the total population, younger age [odds ratio (OR): 0.87 for each additional year; 95% CI 0.80-0.95], being male instead of female (OR 2.96; 95% CI 1.19-7.44), less alcohol intake (OR 0.49; 95% CI 0.20-1.19), working instead of retirement (OR 9.37; 95% CI 1.83-48.04), and more disability at baseline (OR 1.08; 95% CI 1.00-1.16) were found to be predictive of high societal costs. Working was found to be the strongest predictor for high societal costs. After internal validation, the model's fit was good, it's explained variance was moderate (28%) and their AUCs could be interpreted as moderate (0.85). For non-pensioners, the same predictive factors were identified as for the entire population. The costs for the retired participants showed too little variation to be able to predict high costs. CONCLUSIONS: This study estimated the mean total annual societal cost of older adults seeking chiropractic care due to a new episode of LBP at €5297 (95% CI 4191-6403).These costs were mainly due to high levels of presenteeism, and extensively differed based upon work status.