Table 3.
Assessment of additional potential confounders pertinent to studies wherein common infectious diseases (CIDs) were assessed.
| Additional Potential Confounders Considered in Scoring Criteria #6, #10, and #11 of the NIH Quality Appraisal Tool | Children | Adults | Elderly | Accounted For | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Merenstein et al. [24] |
Prodeus et al. [2] |
Guillemard et al. [39] |
Pereg et al. [49] | Tiollier et al. [50] |
Boge et al. ([40], Pilot and Confirmatory Studies) Pilot Study |
Boge et al. ([40], Pilot and Confirmatory Studies) Confirmatory Study |
Guillemard et al. [42] |
Turchet et al. [41] |
||
| 6. Were the groups similar at baseline on important characteristics that could affect outcomes (e.g., demographics, risk factors, and co-morbid conditions)? a | Partially | ✓ | ✓ | NR | NR | ✓ | ✓ | ✓ | Partially b | 5/9 |
| (1) Presence of CIDs at baseline | ✓ | ✓ | ✓ | NR | NR | ✓ | ✓ | ✓ | ✓ | 7/9 |
| (2) Influenza or rotavirus vaccination status at baseline | NR | ✓ | ✓ | NR | NR | ✓ | ✓ | ✓ | ✓ | 6/9 |
| (3) Medication/supplement use at baseline (e.g., proton pump inhibitors) | ✓ | ✓ | ✓ | NR | NR | ✓ | ✓ | ✓ | ✓ | 7/9 |
| 10. Were other interventions avoided or similar in the groups (e.g., similar background treatments)? c | ✓ | ✓ | ✓ | NR | Partially | Partially | Partially | ✓ | NR/No | 4/9 |
| (1) Use of rescue medications/supplements during study (e.g., for colds, flu, or diarrhea) | ✓ | ✓ | ✓ | NR | NR | NR | NR | ✓ | NR | 4/9 |
| (2) Consumption of other probiotics during study | ✓ | ✓ | ✓ | NR | ✓ | ✓ | ✓ | ✓ | No | 7/9 |
| 11. Were outcomes assessed using valid and reliable measures, implemented consistently across all study participants? d | Partially | ✓ | Partially | Partially | Partially | NR | NR | ✓ | Partially | 2/9 |
| (A) Incidence of CIDs | Partially | ✓ | ✓ | Partially | Partially | NR | NR | ✓ | ✓ | 4/9 |
| (1) Diagnosed by a physician/health professional | No | ✓ | ✓ | No | No | NR | NR | ✓ | ✓ | 4/9 |
| (2) If not diagnosed, type of symptoms listed (e.g., sneezing or runny nose) | ✓ | NA | NA | ✓ | ✓ | NR | NR | NA | NA | 3/5 |
| (3) If not diagnosed, number and duration of symptoms used to define a CID episode (e.g., must have at least two symptoms within two consecutive days) | NR | NA | NA | NR | ✓ | NR | NR | NA | NA | 1/5 |
| (B) Duration of CIDs: how duration was determined (e.g., first to the last day of symptoms) | Not assessed | ✓ | NR | NR | NR | NR | NR | ✓ | NR | 2/8 |
| (C) Severity of CIDs: how severity was determined (e.g., scoring system: mild, moderate, or severe) | Not assessed | ✓ | ✓ | Not assessed | ✓ | NR | NR | ✓ | NR | 4/7 |
✓: yes; CID: common infectious disease; NIH: National Institutes of Health; NR: not reported. a In addition to general demographic characteristics (e.g., age and gender), the following characteristics at baseline were considered: 1) the presence of CIDs; 2) influenza or rotavirus vaccination status; and 3) medication/supplement use (e.g., proton pump inhibitors). b The following was reported in the study: “The mean age of the treatment group was 67.1 ± 6.0 years, and for the control group 69.3 ± 5.6 [years]. Although this difference was statistically significant, it is not considered clinically significant.” However, age is considered an important confounder particularly in this population group of elderly subjects. The p-value for the significant difference in age was not reported in the study. c The following other interventions/background treatments during the study were considered: 1) the use of rescue medications/supplements (e.g., for colds, flu, or diarrhea); and 2) the consumption of other probiotics. d The following characteristics related to the measures used to assess the outcomes were considered: A) the incidence of CIDs: 1) diagnosed by a physician/health professional; 2) if not diagnosed by a physician/health professional, the type of symptoms listed (e.g., sneezing or runny nose); and 3) if not diagnosed by a physician/health professional, the number and duration of symptoms used to define a CID episode (e.g., must have at least two symptoms within two consecutive days); B) the duration of CIDs: how duration was determined (e.g., first to the last day of symptoms); C) the severity of CIDs: how severity was determined (e.g., scoring system: mild, moderate, or severe).