Table 1.

Duration of use of NSAIDs and naproxen among current users (use within a month) and risk of MI according to different definitions of the interval between consecutive prescriptions*

	Interval = 7 days	Interval = 30 days	Interval = 60 days
	OR (95%CI) †	OR (95%CI) †	OR (95%CI) †
NSAIDs
Dura 0–30 days	0.97 (0.83–1.14)	1.00 (0.82–1.21)	1.13 (0.92–1.40)
Dura 31–365 days	1.14 (0.97–1.34)	1.04 (0.89–1.23)	1.00 (0.83–1.19)
Dura >365 days	1.31 (0.94–1.81)	1.21 (1.00–1.48)	1.10 (0.93–1.30)
Naproxen‡
Dura 0–30 days	0.81 (0.49–1.35)	0.95 (0.52–1.75)	0.91 (0.46–1.79)
Dura > 30 days	0.94 (0.61–1.45)	0.86 (0.58–1.27)	0.88 (0.60–1.28)

* Duration of use was computed adding the periods of "consecutive" prescriptions, defined as varying intervals between the end of supply of one prescription and the date of prescription of the subsequent one.

† Estimates are adjusted for sex, age, calendar year, anemia, smoking status, alcohol use, diabetes, hypertension, hyperlipidemia, BMI, RA, OA, prior cardiovascular disease, use of steroids, anticoagulants, aspirin, paracetamol, and NSAIDs.

‡ Due to the limited number of observations in the duration strata of 31–365 days and the lack of heterogeneity in estimates of risk between this strata and the duration strata of greater than one year, we collapsed the two of them into one single duration strata.