Economic impact of switching to fixed-dose combination therapy for Japanese hypertensive patients: a retrospective cost analysis

Table 3 Results of DID estimations of antihypertensive drug costs

	Estimate	Standard error	t	p
Total patients n = 10,206	-10420	672	-15.51	<.0001
ARB and CCB combination before index n = 5674	-12800	836	-15.32	<.0001
ARB alone before index n = 4042	2376	1252	1.90	0.0577
Prescribed by doctors at clinics n = 1104	-8815	1411	-6.25	<.0001
Prescribed by cardiovascular specialists n = 2629	-11081	1302	-8.51	<.0001

Difference-in-differences (DID) estimates were obtained by adjusting for gender, age category, number of drugs (≥7), diabetes drug users, and hyperlipidemia drug users. Antihypertensive drug costs were calculated by sum of reimbursement costs for angiotensin-receptor blockers (ARB), angiotensin-converting enzyme inhibitors, dihydropyridine calcium-channel blockers (CCB), thiazide diuretics, beta-blockers, alpha and beta-blockers, and fixed-dose combination drugs.

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