Background: Arthritis and arthralgia are painful symptoms experienced by many elderly patients during hospitalization. Crystal-induced arthritis (CIA) is one of the most common causes of arthritis worldwide and represents the most common cause of acute arthritis in the elderly.  

Objective: To determine the incidence of both acute new onset or acute exacerbation of CIA among elderly patients hospitalized due to an acute medical illness.

Method: This study comprised 85 patients. Patients aged 70 years and older who complained of any articular pain were included in the study. Exclusion criteria were signs of septic arthritis, chronic use of steroids or non-steroidal anti-inflammatory drugs, or admission to the hospital due to an acute attack of CIA. 

Results: Synovial aspiration was performed in 76 patients (89%). Joint aspiration yielded a diagnosis in 67 of them (79%). The predominant type of crystal was calcium pyrophosphate dehydrate (68%) followed by monosodium urate (20%). The main causes of hospitalization were acute infectious disease (57%) followed by neurologic and cardiac diseases, 14% and 9% respectively, and orthopedic problems (6%). Among patients with acute infectious disease, the main causes were pulmonary (57%) and gastrointestinal (22%) infections. In 9 patients (12%) who underwent synovial aspiration, visible crystals were identified without a definite diagnosis.

Conclusion: Our study showed that hospitalization could be a risk factor for the development of CIA, and the time to diagnose CIA is during hospitalization for other acute illnesses.