Table 2.
Characteristics of Published Cohort Studies Exploring the Association Between Smoking and Nasopharyngeal Carcinoma, 1979–2011
| First Author, Year (Reference No.) | Region | Source of Cohort | No. of Cases | Cohort Size | Quality Scorea | Adjustment Variables |
|---|---|---|---|---|---|---|
| Chow, 1993 (15) | United States | Veterans | 48 | 248,046 | 5 | Age, calendar year |
| Zhang, 2004 (48) | Guangzhou, China | Workers | 75 | 80,987 | 5 | Age, sex, education, marital status, alcohol consumption, occupation, exposure to dust |
| Friborg, 2007 (26) | Singapore | Population-based | 173 | 61,320 | 11 | Age, sex, dialect group, year of interview, consumption of preserved protein foods, consumption of fresh vegetables, family history of nasopharyngeal carcinoma |
| Hsu, 2009b (27) | Taiwan | Population-based | 32 | 9,622 | 12 | Age, combination of 2 anti–Epstein-Barr virus seromarkers |
a Summary score for the 6 aspects of methodological quality in the Newcastle-Ottawa Scale guidelines (24), including case definition, representativeness of the exposed cohort, adjustment, measurement of the exposure, follow-up period, and the proportion of subjects lost to follow-up. A score of 12 represented the highest-quality studies.
b Results were limited to men.