Ethnicity	Test-negative & disease-negative patients (d)	Total disease- negative patients (e)	Specificity (d/e×100)
Asian	2545	5223	48.7% (47.4% to 50.1%)
Other	3280	6297	52.1% (50.1% to 53.3%)
All	5825	11520	50.1% (49.6% to 51.5%)