Calcium pyrophosphate deposition disease (CPDD) is arthritis caused by calcium pyrophosphate (CPP) crystal deposition in joints. It is commonly associated with aging as well as a handful of metabolic syndromes. Recent epidemiologic studies suggest a positive association of CPDD and rheumatoid arthritis (RA). Yet how these diseases are related remains unclear. We set out to describe 21 well-characterized patients with both diagnoses.
Medical records of patients with both RA and CPDD identified at a single academic practice site were reviewed for age, gender, age of CPDD and RA onset, disease duration, joint involvement, and lab values including rheumatoid factor (RF), cyclic citrullinated peptide antibody (CCP), iron studies, and parathyroid hormone and calcium levels.
The mean age of CPDD onset was 69.5 ± 11.4 years, with a mean RA age onset of 53.9 ± 16 years, demonstrating a mean lag of 13.4 ± 10.9 years between diagnoses. The majority of RA patients were diagnosed with CPDD based on the presence of radiographic chondrocalcinosis (15/21). The most commonly involved joint was the knee, followed by the wrist, hip, and shoulder.
These data show that the diagnosis of RA often precedes the diagnosis of CPDD. This asynchronous presentation taken together with the classic age of onset for CPDD and typical pattern of joint involvement supports the hypothesis that CPDD develops in RA patients through similar processes as those that cause the idiopathic forms of this disease.