Prevalence and factors associated to crowned dens (CD) and CD syndrome in patients with calcium pyrophosphate arthritis (CPPA)

 

Ana M. Herrero-Beites, Leire Suarez-Zorrilla, Elena Garmendia-Sanchez, Consuelo Modesto-Caballero, Fernando Perez-Ruiz

 

Affiliation(s):

Gorliz Hospital, Rehabilitation Division, And Cruces University Hospital, Rheumatology Division

 

 

Background: CD is a periodointoid ligament calcification by pyrophosphate crystals highly specific for the diagnosis of CPA, and therefore one of the two definite criteria, along with CPP crystals in synovial fluid, for classification.

Objective: to study the prevalence, associated factors, and clinical manifestations associated to CD, including CD syndrome.

Method: retrospective study of patients fulfilling classification criteria for CPPA. CD was defined as periodontoid calcification in CT a scan. We searched for any CT scan including the whole atloid-odontoid joint to evaluate the presence of CD. The cohort database includes general variables (gender, age, time from onset, CPPA clinical phenotype, joint prothesis surgery), chemistry (Mg, Ca, P, ferritin, transferrin saturation, Pth, and 25-OH-vitamin D), an also diuretics, vitamin D, and calcium supplement prescription. CDS was defined as acute, intense cervical pain with elevated CRP, with or without cervical spinal cord compression manifestations, and the presence of CD in TC a scan. 

The electronic file includes any clinical evaluation, all analysis, and all imaging procedures performed to any patient in the public health system for a 2.2 million population with merely 100% free public health use. 

Results: an evaluable CT scan imaging was retrieved from 173/328 (52.7%) patients, 104 women (60.1%) and 69 men, with a mean age of 80±10 years (interquartile range 75-87), and mean time from onset of first symptom 8±5 years (interquartile range 3-12).

CT scans disclosed CD in 102/173 (59.0%) patients, 27/173 (15.6%) with CD syndrome. Considering only those patients with CD in CT scans, no symptom was retrieved in 75/102 (73.5%). In 27 (26.5%) we considered that there were clinical data to support a diagnosis of CD syndrome. 22/102 (21,6%) suffered acute, excruciating cervical pain. 5/102 (4.9%) showed associated spinal cord compression: 2 underwent surgery, and 3 died (in two cases due to complications of preexistent pathologies, one very ancient patient because she refused surgery). 

Factors associated to CD are shown in Table 1. Although 25-OH-D3 was associated to CD, no cut-off (including 10, 20 and 30 pg/ml) showed an association.

In multivariate analysis, only age and time from onset remained statistically significant for CD. 

CD syndrome was associated to chronic inflammatory phenotype (22/63, 34.9% vs. 5/39, 12.8%, p= 0.021) and closely to oligo-polyarticular distribution (23/74, 31.1% vs.4/28, 14.3%, p= 0.086).

Limitations: this is a hospital-bases series, subject to selection bias of patients derived to the rheumatology/emergency room departments.

Conclusions: CD is frequent in patients with CPPA in whom a CT scan is available, mostly associated to aging and longstanding disease. CD syndrome seems to be associated with the most severe clinical phenotype. Available brain/cervical CT scans should be investigated for the presence of CD in patients with CPPA to identify patients at high risk of CD