JAMA 2010;303:1738-46 [JAMA Abstract]
Coeliac disease is difficult to diagnose in primary care, where patients present with non-specific symptoms such as diarrhoea, abdominal pain, or weight loss. Serological tests can help, but which ones? Blood tests for IgA antitissue transglutaminase antibodies (IgA-tTG) and IgA antiendomysial antibodies (EmA) looked most useful in a systematic review.
The authors reviewed 16 studies of unselected adults with abdominal symptoms, three of which were done in well defined primary care settings. They pooled results where they could and reported a sensitivity of 0.89 (95% CI 0.82 to 0.94), a specificity of 0.98 (0.95 to 0.99), a positive likelihood ratio of 37.7, and negative likelihood ratio of 0.11 for IgA antitissue transglutaminase antibody tests.
Corresponding figures for IgA antiendomysial antibodies were 0.90 (0.80 to 0.95), 0.99 (0.98 to 1.00), 171, and 0.11.
A combination of the two tests performed even better, although the evidence was limited. In practice, the simpler IgA-tTG test should probably be done first, say the researchers, while we await for trials testing different sequential strategies for adults presenting specifically to primary care.