Empirical analysis shows reduced cost data collection may be an efficient method in economic clinical trials

Table 6 Percentage change in variance of the estimate: complete cost collection vs. incomplete cost collection

	Complete cost collection	Incomplete cost collection
		Extrapolation						Interpolation
	Alt 0^a	Alt 1^b		Alt 2^c		Alt 3^d		Alt 4^e		Alt 5^f		Alt 6^d
Cost category	(SD)	(SD)	shift	(SD)	shift	(SD)	shift	(SD)	shift	(SD)	shift	(SD)	shift
Sum of direct healthcare costs	(936.67)	(946.22)	1.02	(962.29)	2.74	(997.06)	6.45	(917.58)	−2.04	(962.72)	2.78	(936.79)	0.01
Sum of direct non-healthcare costs	(2568.91)	(2534.07)	−1.36	(2589.39)	0.80	(2598.16)	1.14	(2534.93)	−1.32	(2611.32)	1.65	(2577.07)	0.32
Sum of costs	(2864.38)	(2827.43)	−1.29	(2882.21)	0.62	(2893.05)	1.00	(2807.64)	−1.98	(2911.74)	1.65	(2836.42)	−0.89

^aAlternative 0, complete cost collection.
^bAlternative 1, incomplete cost collection, omitted quarter 2, replaced by quarter 3.
^cAlternative 2, incomplete cost collection, omitted quarter 3, replaced by quarter 4.
^dAlternative 3, incomplete cost collection, omitted quarters 2 and 3, replaced by quarter 4.
^eAlternative 4, incomplete cost collection, omitted quarter 2, replaced by quarters 1 and 3.
^fAlternative 5, incomplete cost collection, omitted quarter 3, replaced by quarters 2 and 4.
^gAlternative 6, incomplete cost collection, omitted quarters 2 and 3, replaced by quarters 1 and 4.

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