Table 2.

Distribution of oral metronidazole exposure in cases and controls

Oral metronidazole usea	Cases		Controls
	N	(%)	N	(%)
No prescription	5,696	95.00	59,491	98.04
Current (<31 days)
Single regimen	14	0.23	19	0.03
Combined regimenb	48	0.80	25	0.04
Recent (31–180 days)
Single regimen	16	0.27	129	0.21
Combined regimenb	49	0.82	151	0.25
Past (181–365 days)
Single regimen	21	0.35	118	0.19
Combined regimenb	41	0.68	153	0.25
Former (>365 days)
Single regimen	44	0.73	245	0.40
Combined regimenb	67	1.12	350	0.58

Notes:

^aBefore index date;

^bcombined metronidazole regimens were defined as at least 1 prescription of PPIs in combination with amoxicillin, tetracycline, or macrolide antibacterials, within 15 days before or after the latest metronidazole prescription, or at least 1 prescription of β-lactam, aminoglycoside, quinolone, vancomycin, or combinations of sulfonamides and trimethoprim antibacterials within 15 days before or after the latest metronidazole prescription. Use of metronidazole outside such combinations was considered single regimen.

Abbreviation: PPI, proton pump inhibitor.