Use of routinely collected health data in randomised clinical trials: comparison of trial-specific death data in the BOSS trial with NHS Digital data

Table 1 For each data source, the numbers of deaths in each year only known from that data source, including the year at which the death was known

a: Deaths available only in trial-specific data collection
Year of event	Year of freeze
Year of event	2013	2014	2015	2016	2017	2018*	Total
2013	4	3	2	2	2	2	15
2014	–	6	4	3	3	3	19
2015	–	–	0	0	0	0	0
2016	–	–	–	6	5	3	14
2017	–	–	–	–	5	0	5
2018	–	–	–	–	–	3	24
Total	4	9	6	11	15	11	56
b: Deaths available only in the NHS Digital dataset
Year of event	Year of freeze
Year of event	2013	2014	2015	2016	2017	2018	Total
2013	21	9	5	4	4	4	47
2014		22	18	4	4	4	52
2015	–	–	62	16	16	12	106
2016	–	–	–	23	11	6	40
2017	–	–	–	–	57	15	72
2018	–	–	–	–	–	27	212
Total	21	31	85	47	92	68	344

The total number of deaths only in one data source in each year is given in the total column. The columns to the left are a breakdown of the total. They show when the death first appeared in the dataset
*For example, in 2018, of the 11 deaths only available in the trial-specific data collection (Table 1), two were known of in 2013, three in 2014, three in 2016 and three new in 2018. With the assumption that deaths from 2013 and 2014 will not be found after 2018, two plus three deaths result in five deaths only in trial-specific data and completely missing from NHS Digital data

ISSN: 1745-6215