Table 5.

MSS and ASN with a combination of OF-type and PC-type boundaries for two endpoints (EP1 and EP2). The MSS per intervention group (equally-sized groups: r =1) is calculated to detect a joint effect on the two endpoints with a power of 80% using one-sided test with a significance level of α = 2.5%, where ρ₁₂ = 0. Both of efficacy and futility assessments are conducted based on DF-1 and critical boundaries are determined using the LD error-spending function with equally-spaced increment in information. The ASN is calculated under H₁.

Standardized mean difference (Δ1,Δ2)	The number of analyses
	Boundary-type		L = 2		L = 3		L = 4
	EP1	EP2	MSS	ASN	MSS	ASN	MSS	ASN
(0.1,0.2)	OF	OF	1658	1473	1734	1385	1782	1343
	OF	PC	1659	1458	1735	1378	1783	1336
	PC	OF	2005	1381	2174	1376	2264	1338
	PC	PC	2005	1352	2174	1273	2264	1236
(0.2,0.2)	OF	OF	529	500	548	468	560	456
	OF	PC	592	510	628	482	648	468
	PC	PC	649	470	700	450	728	438