What is the impact of hypogammaglobulinemia on the rate of infections and survival in solid organ transplantation? A meta-analysis

Hypogammaglobulinemia has been described after solid organ transplantation and has been associated with increased risk of infections. The aim of the study was to evaluate the rate of severe hypogammaglobulinemia and its relationship with the risk of infections during the first year posttransplantation. Eighteen studies (1756 patients) that evaluated hypogammaglobulinemia and posttransplant infections were included. The data were pooled using the DerSimonian and Laird random-effects model. Q statistic method was used to assess statistical heterogeneity. Within the first year posttransplantation, the rate of hypogammaglobulinemia (IgG < 700 mg/dL) was 45% (95% CI: 0.34-0.55; Q = 330.1, p < 0.0001), the rate of mild hypogammaglobulinemia (IgG = 400-700 mg/dL) was 39% (95% CI: 0.22-0.56; Q = 210.09, p < 0.0001) and the rate of severe hypogammaglobulinemia (IgG < 400 mg/dL) was 15% (95% CI: 0.08-0.22; Q = 50.15, p < 0.0001). The rate of hypogammaglobulinemia by allograft type: heart 49% (21%-78%; Q = 131.16, p < 0.0001); kidney 40% (30%-49%; Q = 24.55, p = 0.0002); liver 16% (0.001%-35%; Q = 14.31, p = 0.0002) and lung 63% (53%-74%; Q = 6.85, p = 0.08). The odds of respiratory infection (OR = 4.83; 95% CI: 1.66-14.05; p = 0.004; I(2) = 0%), CMV (OR = 2.40; 95% CI: 1.16-4.96; p = 0.02; I(2) = 26.66%), Aspergillus (OR = 8.19; 95% CI: 2.38-28.21; p = 0.0009; I(2) = 17.02%) and other fungal infections (OR = 3.69; 95% CI: 1.11-12.33; p = 0.03; I(2) = 0%) for patients with IgG < 400 mg/dL were higher than the odds for patients with IgG > 400 mg/dL. The odds for 1-year all-cause mortality for severe hypogammaglobulinemia group was 21.91 times higher than those for IgG > 400 mg/dL group (95% CI: 2.49-192.55; p = 0.005; I(2) = 0%). Severe hypogammaglobulinemia during the first year posttransplantation significantly increased the risk of CMV, fungal and respiratory infections, and was associated with higher 1-year all-cause mortality.