Table 3.
Characteristics of studies missed by the review of reviews approach
| Sample size | Subtype | Studies missed by the ROR search* | |
|---|---|---|---|
| N | % | ||
| Interventions studied in one or more arm | Surgery | 15 | 60 |
| Radiation therapy | 15 | 60 | |
| Ablative therapy | 10 | 40 | |
| Comparators | Active treatment comparator | 15 | 60 |
| Conservative treatment comparator | 8 | 32 | |
| No comparator | 8 | 32 | |
| Study design | Randomized and non-randomized trials | 1 | 4 |
| Observational studies | 24 | 88 | |
| Single arm studies or within-treatment comparisons† | 2 | 8 | |
| Year of publication | 2014 | 3 | 12 |
| 2015 | 6 | 24 | |
| 2016 | 7 | 28 | |
| 2017 | 8 | 32 | |
| 2018 | 1 | 4 | |
| Total | 25‖ | 100.0 | |
*Studies may have multiple arms; percentages do not sum to 100
†Single-arm studies (or within-treatment comparisons) were eligible only for ablative therapies
‖The ROR approach missed a total of 26 eligible citations, which one was a companion study and one was the Fenton et al. review. The analysis is limited to the 25 primary studies
Abbreviations: N number, NA not applicable, RCT randomized controlled trial, ROR review of reviews