Nailfold capillary density in inflammatory bowel disease: Associations with disease activity and systemic inflammation.

Background

Nailfold capillaroscopy offers a non-invasive window into the peripheral microcirculation, but its relevance to inflammatory bowel disease (IBD) activity remains uncertain. We aimed to evaluate capillaroscopic abnormalities in adults with IBD and determine whether capillary density is associated with clinical activity and systemic inflammation.

Methods

This prospective case-control study included 85 adults with IBD and 41 age-matched healthy controls. Disease activity was assessed using the total Mayo score in ulcerative colitis and the Crohn's Disease Activity Index in Crohn's disease. Nailfold capillaroscopy was performed on eight fingers using standardized imaging. Capillaroscopic findings were compared across active disease, remission, and control groups. Multivariable regression and receiver operating characteristic analyses evaluated adjusted associations and discrimination.

Results

Of 85 patients with IBD, 73 had active disease and 12 were in remission. Median capillary density was 6.62 capillaries/mm in active disease, 7.94 in remission, and 8.25 in controls (p < 0.001). Dilated and tortuous capillary counts also differed across groups (p < 0.001 and p = 0.001). Density correlated with CRP (ρ = -0.388), erythrocyte sedimentation rate (ρ = -0.312), total Mayo score (ρ = -0.447), and Crohn's Disease Activity Index category (ρ = -0.499). Active disease remained independently associated with lower density (β = -1.251; p = 0.001). In ulcerative colitis, the association persisted after CRP adjustment (β = -0.099; p = 0.014). The CRP-density model yielded an AUC of 0.944 (95% CI, 0.885-0.986), exceeding CRP alone (DeLong p = 0.037), with an optimism-corrected AUC of 0.938. These findings should be interpreted in the context of the small remission subgroup.

Conclusions

Nailfold capillary density appears to capture a microvascular dimension of IBD activity. In this single-center cohort, combining capillary density with CRP improved discrimination of active disease and provided complementary information beyond CRP.