Patients with ankylosing spondylitis have a higher risk of developing kidney stones, according to a study published in Archives of Rheumatology.
A population-based cohort study in Taiwan showed that newly diagnosed nephrolithiasis (kidney stone formation) was 19% more common in patients with ankylosing spondylitis compared to individuals without the disease.
Ankylosing spondylitis (AS) is a type of arthritis that mainly affects the back. Symptoms include back pain and stiffness, and pain and swelling in other parts of the body caused by inflammation of the joints (arthritis) and inflammation where a tendon joins a bone (enthesitis).
Dr Wen Chi Chen, from China Medical University Hospital in Taichung City, and colleagues analysed data on 3,334 AS patients and 13,336 non-AS patients who had been followed-up on an average of 6.78 years and 6.75 years, respectively, between January 2000 and December 2008.
Patients with a history of kidney stones and those who were younger than 20 years were excluded from the study.
Various comorbidities (one or more additional diseases or disorders) were seen more often among patients than controls, including diabetes, hypertension, hyperlipidemia, gout, coronary heart disease and osteoporosis, MedPageToday reported.
The percentage of newly diagnosed nephrolithiasis was 4.8% in all study subjects. Among the AS patient group it was 5.76%, and among the controls the percentage was 4.58%.
After adjusting for the patients´ sex, age, urban residence and comorbidities, the hazard ratio stood at 1.19.
The research also confirmed that men, with or without ankylosing spondylitis, tend to have a higher risk of developing kidney stones.