Table 5. Studies of Birth Order Without Control Group in a Systematic Review, up to 2012.
| First Author, Year (Reference No.) | Region | StudyDesign | Age Range, Yearsa | Outcome | Birth Order | Observed Distribution | Expected Distribution | Greenwood-Yule Method | Haldane-Smith Method |
| Cai, 2003 [36] | Haimen, China | Case series | >36 | HCC | 1st | 29 | 26.27 | 1.10 | Observed<Expected, t = 2.17, df = 121, P = 0.03 |
| 2nd | 28 | 22.27 | 1.26 | ||||||
| 3rd | 18 | 17.27 | 1.04 | ||||||
| 4th | 9 | 12.94 | 0.70 | ||||||
| ≥5th | 10 | 15.30 | 0.65 | ||||||
| Cao, 2005 [37] | Luoyang, China | Case series | Adults | HCC | 1st | 19 | 16.75 | 1.13 | Observed<Expected, t = 0.95, df = 62, P = 0.4 |
| 2nd | 15 | 13.75 | 1.09 | ||||||
| 3rd | 11 | 12.25 | 0.90 | ||||||
| 4th | 10 | 9.25 | 1.08 | ||||||
| ≥5th | 8 | 11.00 | 0.73 | ||||||
| Song, 2009 [38] | Shunde, China | Case series | Adults | HCC | 1st | 17 | 13.92 | 1.22 | Observed<Expected, t = 2.20, df = 46, P = 0.03 |
| 2nd | 15 | 10.92 | 1.37 | ||||||
| 3rd | 5 | 7.42 | 0.67 | ||||||
| 4th | 4 | 5.75 | 0.70 | ||||||
| ≥5th | 6 | 8.98 | 0.67 |
Abbreviations: df, degree of freedom; HCC, hepatocellular carcinoma.
a
When age range was not available, study was categorized as children (<20 years old), adults (≥20 years old) or both children and adults.
a
Ratio of observed/expected number is presented.