Brewster et al. (2001) investigated whether there is any relation between socioeconomic status and tumour stage at presentation in patients with breast, colorectal, ovarian, and lung cancer.
This is part of the table they presented:
| Tumour size (mm): | Deprivation group | Total | ||
|---|---|---|---|---|
| Affluent | Middle | Deprived | ||
| n=548 | n=1605 | n=364 | n=2517 | |
| 0-20 | 271 (49.5) | 730 (45.5) | 166 (45.6) | 1167 (46.4) |
| 21-50 | 124 (22.6) | 409 (25.5) | 109 (29.9) | 642 (25.5) |
| >50 | 14 (2.6) | 49 (3.1) | 13 (3.6) | 76 (3.0) |
| Unknown | 139 (25.4) | 417 (26.0) | 76 (20.9) | 632 (25.1) |
| Significance: chi-squared = 9.89, df=6, P=0.13 | ||||
The authors concluded: ‘We found no evidence that patients from deprived communities were likely to present with more advanced disease for breast . . . cancer.’
What is wrong with their analysis?
Brewster DH, Thomson CS, Hole DJ, Black RJ, Stroner PL, Gillis CR. (2001) Relation between socioeconomic status and tumour stage in patients with breast, colorectal, ovarian, and lung cancer: results from four national, population based studies. British Medical Journal 322, 830-831.
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Last updated: 10 August, 2006.