Prevalence and Natural Course of Radiographic C1-2 Osteoarthritis: A CT-based analysis of health-checkup participants

Abstract Purpose: Radiographic C1-2 osteoarthritis (OA) may be detected in populations not selected for neck symptoms, but longitudinal data are limited. We evaluated its prevalence, natural course, and associated factors.Methods: This retrospective cohort study included 689 health-checkup participants with paired whole-body computed tomography examinations at least 5 years apart. C1-2 OA was graded from 0 to 3. Baseline OA was defined as grade 1 or higher, incident OA as progression from grade 0 to grade 1 or higher, and worsening as an increase of at least one grade among participants with baseline grade 1 or 2. Logistic regression was used to identify associated factors.Results: Baseline OA was present in 102 participants (14.8%). Incident OA occurred in 6 of 587 participants (1.0%), and worsening occurred in 22 of 96 participants (22.9%). Baseline OA was independently associated with older age (odds ratio [OR] 1.07, 95% confidence interval [CI] 1.04–1.10), diffuse idiopathic skeletal hyperostosis (OR 1.98, 95% CI 1.11–3.53), a history of spine surgery (OR 15.52, 95% CI 3.19–75.61), and higher hemoglobin A1c (OR 1.68, 95% CI 1.17–2.40). In an exploratory model, higher inorganic phosphorus was associated with worsening (OR 8.47, 95% CI 2.10–34.20).Conclusion: Radiographic C1-2 OA was present in 14.8% of participants and worsened in 22.9% of those with pre-existing grade 1 or 2 OA. Radiographic C1-2 OA should not be equated with symptomatic disease.