Table 1.
Characteristics of Included Studies.
| Characteristics | Included in Statistcal Analysis | Included in OM Meta-Analysis (Fig. 3) | Included in NRM Meta-Analysis (Fig. 2) | Included in RM Meta-Analysis | |
|---|---|---|---|---|---|
| Total Studies | N | 28 | 25 | 8 | 7 |
| Average number of patients per study | N (range) | 151 (25–738) | 162 (26–738) | 191 (25–738) | 229 (26–738) |
| Adult vs. pediatric studies % (age range) | Adult | 9 (32.1%) | 7 (28.0%) | 3 (37.5%) | 3 (42.9%) |
| Pediatric | 8 (28.6%) | 7 (28.0%) | 2 (25.0%) | 1 (14.3%) | |
| Both | 11 (39.3%) | 11 (44.0%) | 3 (37.5%) | 3 (42.9%) | |
| Study Design | Prospective | 16 (57.1%) | 15 (60.0%) | 5 (62.5%) | 4 (57.1%) |
| Retrospective | 12 (42.9%) | 10 (40.0%) | 3 (37.5%) | 3 (42.9%) | |
| Underlying diseases (N patients across all studies) | ALL | 306 (6.2%) | 221 (4.4%) | 160 (12.5%) | 207 (15.5%) |
| AML | 355 (7.3%) | 342 (6.8%) | 206 (16.1%) | 193 (14.5%) | |
| CML | 85 (1.7%) | 78 (1.5%) | 9 (0.7%) | 12 (0.9%) | |
| NHL | 15 (0.3%) | 12 (0.2%) | 7 (0.5%) | 4 (0.3%) | |
| AML or MDS | 146 (2.9%) | 137 (2.7%) | 12 (1%) | 17 (1%) | |
| Myeloma | 157 (3.1%) | 141 (2.8%) | 0 (0.0%) | 16 (1.2%) | |
| Unspecified lymphoma | 286 (5.8%) | 275 (5.4%) | 0 (0.0%) | 11 (0.8%) | |
| Unspecified leukemia | 1490 (40.0%) | 1490 (29.5%) | 0 (0.0%) | 0 (0.0%) | |
| Neuroblastoma | 7 (0.1%) | 7 (0.1%) | 0 (0.0%) | 0 (0.0%) | |
| Unspecified malignancy | 1274 (32.3%) | 1263 (25.0%) | 668 (52.2%) | 657 (49.3%) | |
| Non-malignancy | 509 (10.8%) | 508 (10.0%) | 146 (11.4%) | 145 (10.9%) | |
| Unspecified | 583 (12.6%) | 583 (11.5%) | 72 (5.6%) | 72 (5.4%) | |
| GVHD prophylaxis | CsA | 219 (14.1%) | 219 (13.4%) | 58 (27.6%) | 58 (19.5%) |
| TAC | 89 (5.3%) | 89 (5.4%) | 0 (0.0%) | 0 (0.0%) | |
| MTX | 22 (1.3%) | 3 (0.2%) | 19 (9.0%) | 0 (0.0%) | |
| TAC + MTX | 9 (0.5%) | 9 (0.5%) | 0 (0.0%) | 0 (0.0%) | |
| Sirolimus | 161 (10.0%) | 161 (9.8%) | 0 (0.0%) | 0 (0.0%) | |
| Cyclophosphamide | 101 (6.0%) | 101 (6.2%) | 0 (0.0%) | 0 (0.0%) | |
| ATG | 136 (8.3%) | 136 (8.3%) | 0 (0.0%) | 0 (0.0%) | |
| alemtuzumab | 34 (2.0%) | 34 (2.1%) | 0 (0.0%) | 0 (0.0%) | |
| CsA + prednisolone | 172 (10.7%) | 172 (10.5%) | 0 (0.0%) | 0 (0.0%) | |
| CsA + unspecified steroids | 26 (1.5%) | 26 (1.6%) | 26 (12.4%) | 26 (8.7%) | |
| CsA + MTX | 436 (32.5%) | 431 (26.3%) | 5 (2.4%) | 0 (0.0%) | |
| CsA + MMF | 82 (4.8%) | 82 (5.0%) | 0 (0.0%) | 0 (0.0%) | |
| CsA + MMF + TAC | 53 (3.1%) | 0 (0.0%) | 0 (0.0%) | 53 (17.8%) | |
| MMF + MTX | 3 (0.2%) | 3 (0.2%) | 0 (0.0%) | 0 (0.0%) | |
| CsA MMF + MTX | 174 (10.9%) | 174 (10.6%) | 102 (48.6%) | 102 (34.2%) | |
| TAC/MTX/MMF | 59 (3.4%) | 0 (0.0%) | 0 (0.0%) | 59 (19.8%) | |
| Conditioning regimen | RIC | 1179 (34.7%) | 1170 (34.6%) | 400 (27.1%) | 391 (27.0%) |
| MAC | 2223 (65.3%) | 2207 (65.4%) | 1074 (72.9%) | 1058 (73.0%) | |
| Studies that administered antiviral prophylaxis (N) | ACY | 12 (42.9%) | 10 (40.0%) | 2 (25.0%) | 2 (28.6%) |
| GAN | 2 (7.1%) | 2 (8.0%) | 0 (0.0%) | 0 (0.0%) | |
| ACY and GAN | 4 (14.3%) | 4 (16.0%) | 1 (12.5%) | 1 (14.3%) | |
| IVIg | 1 (3.6%) | 0 (0.0%) | 1 (12.5%) | 0 (0.0%) | |
| Unclear or ND | 9 (32.1%) | 9 (36.0%) | 4 (50.0%) | 4 (57.1%) | |
| Outcomes reported | (Range of mortality %) | 4–65% | 7–65% | 4–42% | 6–30% |
| Mean follow-up period | (Days and range) | 99.9 (28–365) | 99.9 (28–365) | 87.6 (28–120) | 87.6 (28–120) |
| HHV-6 Monitoring frequency | 2x per week | 1 (3.6%) | 1 (4.0%) | 0 (0.0%) | 0 (0.0%) |
| 1x per week | 15 (53.6%) | 12 (48.0%) | 4 (50.0%) | 3 (42.9%) | |
| 1x per 2 weeks | 1 (3.6%) | 1 (4.0%) | 0 (0.0%) | 0 (0.0%) | |
| Other | 5 (17.9%) | 5 (20.0%) | 2 (25.0%) | 2 (28.6%) | |
| Unclear or ND | 6 (21.4%) | 6 (24.0%) | 2 (25.0%) | 2 (28.6%) | |
| Samples used for testing (N) | Whole blood | 5 (17.9%) | 5 (20.0%) | 0 (0.0%) | 0 (0.0%) |
| Plasma | 17 (60.7%) | 16 (64.0%) | 7 (87.5%) | 6 (85.7%) | |
| PBMC | 3 (10.7%) | 2 (8.0%) | 1 (12.5%) | 0 (0.0%) | |
| Unclear or ND | 3 (10.7%) | 2 (8.0%) | 0 (0.0%) | 1 (14.3%) | |
| Threshold for HHV-6 detection, copies/mL (N) | 1000 | 4 (14.3%) | 4 (16.0%) | 1 (12.5%) | 1 (14.3%) |
| 500 | 3 (10.7%) | 3 (12.0%) | 1 (12.5%) | 1 (14.3%) | |
| 200 | 1 (3.6%) | 1 (4.0%) | 0 (0.0%) | 0 (0.0%) | |
| 125 | 1 (3.6%) | 1 (4.0%) | 1 (12.5%) | 1 (14.3%) | |
| 120 | 1 (3.6%) | 1 (4.0%) | 0 (0.0%) | 0 (0.0%) | |
| 100 | 2 (7.1%) | 2 (8.0%) | 1 (12.5%) | 1 (14.3%) | |
| 50 | 3 (10.7%) | 3 (12.0%) | 0 (0.0%) | 0 (0.0%) | |
| 25 | 3 (10.7%) | 3 (12.0%) | 1 (12.5%) | 1 (14.3%) | |
| 20 | 1 (3.6%) | 1 (4.0%) | 0 (0.0%) | 0 (0.0%) | |
| 10 | 1 (3.6%) | 1 (4.0%) | 0 (0.0%) | 0 (0.0%) | |
| Unclear or ND | 8 (28.6%) | 5 (20.0%) | 3 (37.5%) | 2 (28.6%) | |
| Type of HCT | BMT | 921 (16.5%) | 850 (15.7%) | 154 (11.8%) | 914 (76.0%) |
| CBT | 753 (13.5%) | 750 (13.8%) | 864 (66.1%) | 289 (24.0%) | |
| PBSC | 1382 (24.7%) | 1292 (23.8%) | 289 (22.1%) | 0 (0.0%) | |
| Unspecified | 2538 (45.4%) | 2538 (46.7%) | 0 (0.0%) | 0 (0.0%) |
ALL Acute lymphoblastic leukemia, AML acute myeloid leukemia, CML chronic myeloid leukemia, NHL Non-Hodgkin lymphoma, MDS Myelodysplastic syndrome, RIC Reduced-intensity conditioning, MAC myeloablative conditioning, ACY Acyclovir, GAN Ganciclovir, ND Not discussed, OM Overall mortality, RM Relapse mortality, NRM Non-relapse mortality.