Sample size estimation for randomised controlled trials with repeated assessment of patient-reported outcomes: what correlation between baseline and follow-up outcomes should we assume?

Walters, Stephen J.; Jacques, Richard M.; dos Anjos Henriques-Cadby, Inês Bonacho; Candlish, Jane; Totton, Nikki; Xian, Mica Teo Shu

doi:10.1186/s13063-019-3671-2

Trials

Table 1 Summary of the 20 randomised controlled trials

From: Sample size estimation for randomised controlled trials with repeated assessment of patient-reported outcomes: what correlation between baseline and follow-up outcomes should we assume?

	Trial name	Trial population	Age range (years)	Outcome measures	No. of outcomes	Time points post-randomisation	No. of time points	No. of correlations	Sample size at baseline	Max N^a	Reference	Year of publication
1	Leg Ulcer	Leg ulcers	32 to 97	EQ-5D, SF-36	9	3, 12 months	2	18	233	200	[9]	1998
2	NAMEIT	Early severe rheumatoid arthritis	18 to 75	SF-36, SF-6D	9	2, 4, 6, 8, 10, 12 months	6	54	222	222	[10]	2000
3	Homeopathy for CFS	Chronic fatigue syndrome (CFS)	20 to 62	MFI	5	6 months	1	5	103	85	[11]	2004
4	Acupuncture	Low back pain	20 to 64	SF-36	8	3, 12, 24 months	3	24	239	217	[12]	2005
5	Knee Replacement	Osteoarthritis patients undergoing total knee replacement	51 to 92	SF-36, WOMAC	14	3 months	1	14	151	114	[13]	2005
6	FED	Older (aged ≥ 65) hospitalised patients with acute illness	65 to 93	Barthel, SF-36	9	1.5, 6 months	2	18	445	225	[14]	2006
7	AIM-High	Malignant melanoma	18 to 77	EORTC QLQ-C30	15	6, 12, 18, 24 months	4	60	444	392	[15]	2006
8	PoNDER	New mothers	18 to 45	CORE-OM, EPDS,^b SF-36, SF-6D	9	4.5, 10.5, 16.5 months	3	26	2659	2659	[16]	2009
9	COPD	Chronic obstructive pulmonary disease (COPD)	49 to 86	EQ-5D, SF-36, SF-6D	12	2, 6, 12, 18 months	4	48	238	172	[17]	2010
10	Corn Plasters	Foot corns	18 to 90	EQ-5D, EQ-5D VAS, VAS Pain	3	3, 6, 9, 12 months	4	12	201	182	[18]	2013
11	PLINY	Independently living older people (aged ≥ 75)	75 to 95	EQ-5D, EQ-5D VAS, GSES, ONS Well-being, PHQ-9, SF-36	15	6 months	1	15	157	56	[19]	2014
12	3Mg	Adults with acute severe asthma in the emergency department	16 to 88	EQ-5D	1	1 month	1	1	932	437	[20]	2014
13	SELF	Shoulder rotator cuff tendinopathy	23 to 83	SPADI	3	3, 6, 12 months	3	9	85	59	[6]	2016
14	BEADS	Post-stroke depression	31 to 97	EQ-5D, EQ-5D VAS, PHQ-9	3	6 months	1	3	49	39	[21]	2016
15	DiPALS	Amyotrophic lateral sclerosis (ALS)	23 to 83	EQ-5D, SAQLI, SF-36	13	2, 3, 6, 9, 12 months	5	65	74	55	[22]	2016
16	Lifestyle Matters	Independently living older people (aged ≥ 65)	65 to 92	EQ-5D, EQ-5D VAS, GSES, PHQ-9, SF-36	14	6, 24 months	2	28	288	262	[23]	2017
17	IPSU	Women with urinary incontinence and sexual dysfunction	21 to 70	EQ-5D, PISQ-31, SF-36	15	6 months	1	15	107	66	[24]	2018
18	POLAR	Lumbar radicular syndrome (LRS)	23 to 71	Back Pain VAS, EQ-5D, EQ-5D VAS, Leg Pain VAS, ODI	5	1.5, 3, 6 months	3	15	80	73	[25]	2018
19	PRACTICE	COPD	40 to 92	EQ-5D, EQ-5D VAS	2	0.25, 1, 3 months	3	6	55	42	[26]	2018
20	STEPWISE	Schizophrenia	18 to 71	B-IPQ, BPRS, EQ-5D, EQ-5D VAS, PHQ-9, RAND SF-36	14	3, 12 months	2	28	412	358	[27]	2018
								464	7173	5915

^aMax N is the maximum sample size for the baseline and post-randomisation follow-up correlations
^bFor the PoNDER trial the EPDS was measured at baseline and at 4.5 and 10.5 months post-randomisation
Abbreviations: Barthel Barthel Index for Activities of Daily Living (ADL), B-IPQ Brief Illness Perception Questionnaire, BPRS Brief Psychiatric Rating Scale, CORE-OM Clinical Outcomes in Routine Evaluation-Outcome Measure, EORTC QLQ European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire, EPDS Edinburgh Postnatal Depression Scale, EQ-5D EuroQol Five Dimension, GSES General Self-Efficacy Scale, MFI Multidimensional Fatigue Inventory, ODI Oswestry Disability Index, ONS Office for National Statistics Well-being Questionnaire, PHQ-9 Patient Health Questionnaire, PISQ-31 Pelvic Organ Prolapse/Urinary Incontinence Sexual Questionnaire, RAND SF-36 Research and Development 36-item Short Form Survey Instrument, SAQLI Sleep Apnea Quality of Life Index, SF-36 Short Form (36 item) Health Survey, SF-6D Short Form Six Dimension, SPADI Shoulder Pain and Disability Index, VAS visual analogue scale, WOMAC Western Ontario and McMaster Universities Osteoarthritis Index

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ISSN: 1745-6215

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