Data in longitudinal randomised controlled trials in cancer pain: is there any loss of the information available in the data? Results of a systematic literature review and guideline for reporting

Table 1 Description of studies

Pain outcome	Primary only	46 % (34/74)
	Secondary only	22 % (16/74)
	Primary and secondary	23 % (17/74)
	Unclear	9 % (7/74)
Primary pain outcome collected	NRS^a	23 % (17/74)
	VAS^b	28 % (21/74)
	Brief Pain Inventory	31 % (23/74)
	Other instruments	18 % (13/74)
Number of groups	Two	87 % (64/74)
Number of patients	Median (range)	80 (9–2046)
Type of study	Parallel design	43 % (32/74)
	Comparison placebo/usual care	57 % (42/74)
	Cross-over design	18 % (13/74)
Duration of follow-up	Under24h	16 % (12/74)
	Patient dependent	7 % (5/74)
	Other: median (range) of duration	7 (1–260) weeks
Type of pain episodes	Breakthrough	5 % (4/74)
Type of pain episodes	Background	95 % (70/74)

ISSN: 1471-2407