Table 1. Distribution of cases and controls by study recruitment center.

	Study centers
Study status	KCD	KTH	RMH	PPC	KMU	Total
Cases n (%)	57 (67.8)	9 (10.7)	18 (21.4)			84
Controls n (%)	63 (36.2)	36 (20.6)	20 (11.4)	28 (16)	26 (14.9)	174

^{KCD: Khyber College of Dentistry, KTH: Khyber Teaching Hospital, RMH: Rehmat Memorial Hospital, PPC. Pakistan Paraplegic Center, KMU: Khyber Medical University}