Hip osteoarthritis prevalence estimates by three radiographic scoring systems

Objective. To estimate and compare the age- and sex-specific prevalence of radiographic hip osteoarthritis (RHOA) in a population-based study of the Pima Indians, using 3 atlas-based methods for assessing features of RHOA. Methods. Pelvic radiographs from 755 Pima Indians age ≤45 years enrolled in a population-based study were read using the Kellgren/Lawrence (K/L) grading scale (grade 0-4) and 2 validated individual-radiographic-features (IRF) scales (grades 0-3 for narrowing and osteophytes). Results. The age- and sex- specific prevalence of RHOA among Pima Indians assessed using the K/L scale was < 10% in all age and sex groups. The prevalence of grade ≤2 osteophytes assessed using the 2 IRF scales were similar to each other in all age and sex groups. However, differences between the 2 IRF scoring systems were found for the prevalence of grade ≤2 joint space narrowing. Conclusion. Pima Indians have an age- and sex-specific prevalence of RHOA similar to that found in the US population. Our finding of different joint space narrowing prevalence by the 2 IRF grading scales supports the use of the same atlas-based case definitions for determining disease prevalence for comparative studies.