Racial differences in associations between baseline patterns of radiographic osteoarthritis and multiple definitions of progression of hip osteoarthritis: the Johnston County Osteoarthritis Project

BACKGROUND: To identify baseline radiographic features that predict hip osteoarthritis (HOA) progression, and to explore differences in these associations by race. METHODS: Radiographs from the community-based Johnston County OA Project were scored using Kellgren-Lawrence (KL) grade and for presence and location of joint space narrowing (JSN), osteophytes, and subchondral changes. Associations between these features and HOA progression (increase of at least 1 KL grade, interval hip replacement, range of motion [ROM, a reduction of ≥10° in internal rotation], or disability [increase of ≥0.2 in Health Assessment Questionnaire scores], or Any of these) were assessed using logistic regression, adjusting for age, gender, race, hip injury, BMI, education, smoking and follow-up time, accounting for multiple comparisons. Race interactions were assessed and analyses stratified as indicated. RESULTS: The sample (n = 1,422) included 40 % men and 26 % African American (AA) participants, with mean age 61 years and BMI 29 kg/m(2). The baseline frequency of radiographic hip OA (RHOA) between Caucasians and AAs was similar (23 %), although some radiographic features differed. AAs were more likely to have progression defined by ROM or disability or Any progression; Caucasians were more likely to have RHOA progression. JSN, subchondral sclerosis, and medial osteophytes were associated with increased RHOA progression overall; JSN was associated with disability progression only in AAs, while lateral osteophytes were associated with ROM progression only in Caucasians. CONCLUSIONS: AAs and Caucasians exhibited differences in the radiographic presentation and progression patterns of HOA, with AAs reporting progressive pain and disability, while Caucasians had more RHOA progression.