Differences in multijoint radiographic osteoarthritis phenotypes among African Americans and Caucasians: the Johnston County Osteoarthritis project.
OBJECTIVE
To define and contrast multiple joint radiographic osteoarthritis (OA) phenotypes describing hand and whole-body radiographic OA among African Americans and Caucasians.


METHODS
We conducted a cross-sectional analysis in the Johnston County Osteoarthritis Project, using radiographic data for the hands, tibiofemoral (TF) joints, patellofemoral joints, hips, and lumbosacral (LS) spine. Radiographs were read for OA by a single radiologist using standard atlases. Fisher's exact test, with correction for multiple comparisons, was used to compare phenotype frequencies by race and sex. Logistic regression was used to provide odds ratios, which were adjusted for sex, age, and body mass index (BMI).


RESULTS
Sixteen mutually exclusive hand (n = 2,083) and 32 whole-body (n = 1,419) radiographic OA phenotypes were identified. We found that in comparison to Caucasians, African Americans had significantly less frequent radiographic OA of the distal interphalangeal joints, both in isolation and in combination with other hand joint sites, but had comparable frequencies of radiographic OA for other hand joint sites. Moreover, African Americans had less frequent radiographic OA of the hand, both in isolation and in combination with other joint sites, as compared to Caucasians. In contrast, African Americans had more than twice the odds of isolated OA of the TF joint and 77% higher odds of radiographic OA of the TF joint and LS spine together as compared to Caucasians.


CONCLUSIONS
Even after adjustment for sex, age, and BMI, African Americans were less likely than Caucasians to have hand radiographic OA phenotypes, but more likely to have knee radiographic OA phenotypes involving the TF joint. African Americans may have a higher burden of multiple large-joint OA involvement not captured by most definitions of "generalized OA."
Thurston Arthritis Research Center, University of North Carolina, Chapel Hill, NC 27599, USA. aenelson@med.unc.edu
Amanda E
AE
Nelson
Jordan B
JB
Renner
Todd A
TA
Schwartz
Virginia B
VB
Kraus
Charles G
CG
Helmick
Joanne M
JM
Jordan
D001741:Black or African American; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D050823:Hand Joints / Q000000981:diagnostic imaging*; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging*; D016015:Logistic Models; D008161:Lumbosacral Region / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D010003:Osteoarthritis / Q000000981:diagnostic imaging* / Q000453:epidemiology / Q000208:ethnology*; D010641:Phenotype; D015995:Prevalence; D011859:Radiography; D012307:Risk Factors; D044465:White People