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Table 6 Sub-group analysis of item responses by Study Size (in quartiles)

From: Risk of bias of randomized controlled trials published in orthopaedic journals

Randomization Y N DK
Size < 51 35(61.4) 5(8.8) 17(29.8)
51 ≤ size < 81 41(70.7) 5(8.6) 12(20.7)
81 ≤ size < 158 53(84.1) 3(4.8) 7(11.1)
Size ≥ 158 36(59.0) 4(6.6) 21(34.4)
Allocation Concealment
Size < 51 33(57.9) 4(7.0) 20(35.1)
51 ≤ size < 81 42(72.4) 5(8.6) 11(19.0)
81 ≤ size < 158 52(82.5) 3(4.8) 8(12.7)
Size ≥ 158 37(60.7) 3(4.9) 21(34.4)
Blinding of Participants
Size < 51 9(15.8) 10(17.5) 38(66.7)
51 ≤ size < 81 9(15.5) 10(17.2) 39(67.2)
81 ≤ size < 158 15(23.8) 19(30.2) 29(46.0)
Size ≥ 158 16(26.2) 12(19.7) 32(54.1)
Blinding of Assessors
Size < 51 25(43.9) 7(12.3) 25(43.9)
51 ≤ size < 81 30(51.7) 10(17.2) 18(31.0)
81 ≤ size < 158 34(54.0) 9(14.3) 20(31.8)
Size ≥ 158 29(47.5) 12(19.7) 20(32.8)
Outcome Measurement
Size < 51 54(94.7) 1(1.8) 2(3.5)
51 ≤ size < 81 54(93.1) 1(1.7) 3(5.2)
81 ≤ size < 158 61(96.8) 0(0) 2(3.2)
Size ≥ 158 56(91.8) 0(0) 5(8.2)
Similarly Trained Individuals
Size < 51 29(50.9) 1(1.8) 27(47.4)
51 ≤ size < 81 38(65.5) 0(0) 20(34.5)
81 ≤ size < 158 31(49.2) 2(3.2) 30(47.6)
Size ≥ 158 15(24.6) 0(0) 46(75.4)
Compliance with Intervention
Size < 51 28(49.1) 29(5.9) 0(0)
51 ≤ size < 81 39(67.2) 18(31.0) 1(1.7)
81 ≤ size < 158 53(84.1) 10(15.9) 0(0)
Size ≥ 158 46(75.4) 15(24.6) 0(0)
Intent to Treat Analysis
Size < 51 10(17.5) 0(0) 47(82.5)
51 ≤ size < 81 15(25.9) 0(0) 43(74.1)
81 ≤ size < 158 39(61.9) 1(1.6) 23(36.5)
Size ≥ 158 39(63.9) 3(4.9) 19(31.1)
Clustering
Size < 51 0(0) 0(0) 57(100)
51 ≤ size < 81 0(0) 0(0) 58(100)
81 ≤ size < 158 1(1.6) 0(0) 62(98.4)
Size ≥ 158 0(0) 0(0) 61(100)
Similar at Baseline
Size < 51 37(64.9) 2(3.5) 18(31.6)
51 ≤ size < 81 39(67.2) 3(5.2) 16(27.6)
81 ≤ size < 158 47(74.6) 7(11.1) 9(14.3)
Size ≥ 158 45(73.8) 8(13.1) 8(13.1)