Table 1 Literature searching and study identification
N | (%) | |
|---|---|---|
Papers | ||
Identified as potentially relevant | 5993 | 100% |
Not obtainable | 244 | 4.1% |
Obtained | 5749 | 95.9% |
Did not provide relevant data at all | 4901 | 81.8% |
Satisfied inclusion criteria except less than 100 lung cancer cases | 175 | 2.9% |
Satisfied all inclusion criteria | 673 | 11.2% |
Studies | ||
Identified | 287 | 100.0% |
Principal | 267 | 93.0% |
Subsidiary | 20 | 7.0% |