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Table 1 Current causes of missing data within the cohort of Health Technology Assessment Programme (HTA)-funded trials

From: Identifying research priorities for effective retention strategies in clinical trials

Causes of missing data Number of trials (%)
n = 49a
Patients withdrawing 41 (84%)
Losing contact with patients 30 (61%)
Patients not returning questionnaire 24 (49%)
Patient deaths 23 (47%)
Clinicians withdrawing patients 17 (35%)
Patients not attending a visit/clinic 14 (29%)
Missed measurement by clinical staff 12 (25%)
Patient outcomes other than death preventing measurement, e.g. coma, too ill to complete measures 10 (20%)
Data not provided by clinical staff 10 (20%)
Other 6 (12%)
Technology problems 4 (8%)
Laboratory problems 2 (4%)
  1. Survey respondents chose all causes of missing data observed in their trial.aOne person did not complete the question