Background: The aim of the study was to determine the rate of hypogammaglobulinemia and its relationship with the risk of infections during the first year post-transplantation.

Methods: All studies that evaluated hypogammaglobulinemia and post-transplant infections were included. The data was pooled using the DerSimonian and Laird random-effects model. Q statistic method was used to assess statistical heterogeneity.

Results: The analysis included 1609 patients (18 studies), with a mean age of 42 years (SE±5.7) (1232 patients, 15 studies), of which 43% were female (1140 patients, 14 studies). Within the first year post-transplantation the overall rate of hypogammaglobulinemia (IgG<700mg/dl) (1482 patients, 16 studies) was 45% (95%CI 0.34-0.55;Q=330.1;p<0.0001), mild hypogammaglobulinemia (IgG=400-700mg/dl) (669 patients, 8 studies) was 39% (0.22-0.56;Q=210.09;p<0.0001) and severe hypogammaglobulinemia (IgG<400mg/dl) (669 patients, 8 studies) was 15% (0.08-0.22;Q=50.15;p<0.0001). The rate of hypogammaglobulinemia (IgG<700mg/dl) by the type of allograft was: heart (544 patients, 4 studies) 49% (21%-78%;Q=131.16;p<0.0001); kidney (579 patients, 6studies) 39% (30%-49%;Q=25.52;p=0.0001); liver (163 patients, 2 studies) 16% (0.1%-35%;Q=14.31;p=0.0002); lung (196 patients, 4 studies) 63% (53%-74%;Q=6.85;p=0.08).

The mean number of infections per patient was 0.88 (SE± 0.88) for all infections (1144 patients, 14 studies); 0.29 (SE±0.41) for respiratory infections (534 patients, 7 studies); and 0.37 (SE±0.36) for CMV infections (1144 patients, 14 studies). When only patients with hypogammaglobulinemia were analyzed, the mean number per patient of all infections (382 patients, 8 studies), respiratory infections (268 patients, 5 studies) and CMV infections (292 patients, 6 studies) were: 1.3 (SE±1.36); 0.44 (SE±0.67); and 0.50 (SE±0.39).

Compared to controls (IgG>700mg/dl), patients with hypogammaglobulinemia (<700mg/dl) had OR=1.89 ([95% CI 0.79-4.49];p=0.15;I2=81.6%;Q=21.76) for developing infections (5 studies, 1670 patients). The odds for developing CMV infection was significantly higher in patients with severe hypogammaglobulinemia (< 400mg/dl) compared to patients with > 400mg/dl: OR=2.53 ([95% CI 1.37-4.66];p=0.003;I²=3.94%).

Conclusion: During the first year post-transplantation hypogammaglobulinemia was highly prevalent (45%), but the number of infections per patient was not significantly elevated. CMV infections were 2.5 times higher in patients with severe hypogammaglobulinemia.

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