Abnormal IgM levels (1.89 [95% CI: 1.29–2.79]), the presence of ⩾2 comorbidities (1.80 [95% CI: 1.06–3.08]), and having overweight or obesity (1.46 [95% CI: 1.00–2.13]) also retained an association with an increased risk of SIs; it should be noted that among 234 patients with IgM < LLN, 6 (2.6%) patients experienced 29 out of 78 (37.2%) SIs, suggesting a potentially skewed risk association. Here, CD40LG is linked to obesity disorder.