Background: Patients may be asked to register a symptom daily in clinical trials. A problem associated with this kind of registration is that patients do not always fill in the diary at the appropriate time. As there is evidence showing that memory is unreliable, this undermines the entire purpose of collecting daily data on paper diaries. We aimed to compare accuracy, autocorrelations of consecutive entries, and responsiveness in paper diaries (P-Diaries) with electronic diaries (E-Diaries) and telephone diaries (T-Diaries).
Methods: In a multi-centre, open, and parallel trial, 177 patients were allocated at random to P-Diaries, E-Diaries, or T-Diaries for the registration of symptoms through 4 weeks of treatment of gastro-oesophageal reflux disease (GORD). The primary outcome measure was the diaries.
Findings: The proportion of patients completing all morning and all evening entries on time was low for both E-Diary and T-Diary groups. By accepting entries that were done half a day late, the proportion was increased to 19/57 (33%) for the E-Diary group, and to 9/61 (15%) for the T-Diary group. For P-Diary, where no control for time registration and entries was adapted, 37/59 (63%) of the patients completed all morning and all evening entries. A significant higher autocorrelation in P-Diaries was also found. Responsiveness was similar regardless of method of data capture.
Interpretation: The results are consistent with the suggestion that data in the P-Diaries are not filled in at the appropriate time. Use of E-Diaries or T-Diaries improves quality and is recommended in future clinical trials.