Meta-analysis
Two cohort studies reported HR as the measure for the risk of T1DM in
asthmatic patients. There was significant heterogeneity (I ² =
90.2%, P = 0.001). In random-effects model analysis, pooled HR
for the risk of T1DM was 1.30 (95% CI 1.05–1.61, P =0.014).
Figure 2 shows the forest plot of the included studies.
Three studies reported HR as the measure for asthma risk in T1DM
patients. There was significant heterogeneity (I ² = 92.7%,P < 0.001). In random-effects model analysis, pooled HR
was 0.98 (95% CI 0.64–1.51,P =0.941). In the meta-analysis of the 12 studies that reported OR
as the measure for asthma risk in T1DM patients, pooled OR was 0.84,
95% CI 0.65–1.08, P =0.168). Figure 3 shows the forest plot of
the included studies. Subgroup analysis indicated that geographical
location and quality grade could not explain the heterogeneity (Table
S4). In meta-regression analysis, the observed heterogeneity could not
be explained by the year of publication, region, incidence of asthma in
the control group, sample size and quality score (Table S5). Sensitivity
analysis failed to show significant bias caused by any single study
(Figure S1). Funnel plots indicated some degree of publication bias
(Figure S2), but Begg’s test did not confirm the bias (P of
=0.82).