New radiographic grading scales for osteoarthritis of the hand. Reliability for determining prevalence and progression.

We developed and evaluated scales for grading the prevalence and progression of the individual radiographic features of osteoarthritis (OA) of the hand. Four equally time-spaced hand radiographs from 50 participants in the Baltimore Longitudinal Study of Aging, who were followed for at least 20 years, were read separately and "blindly" by 4 experienced, trained readers. Eleven hand joints were individually assessed for the presence of osteophytes, joint space narrowing, subchondral cysts, subchondral sclerosis, lateral deformity, and cortical collapse, and were also graded using the Kellgren/Lawrence scale, a global estimate of OA. The intraclass correlation coefficient was used to determine cross-sectional inter- and intrareader reliability. Interreader agreement on OA progression was evaluated using life-table analysis. Each of the grading scales for the individual radiographic features of OA of the hand, except for cysts, were cross-sectionally reliable between readers. Each reader was able to reproduce his original scores almost perfectly when grading the radiographs a second time. Using these scales, the different readers agreed on all the features of longitudinal progression of OA of the hand, except cysts. We believe that this method for grading hand radiographs for OA has proved to be reliable for both cross-sectional and longitudinal studies.