Published on Thursday November 23, 2017

Smooth Drug Development published an article on efficacy of electronic diaries in clinical research in Pharmvestnik

Electronic Diary in Clinical Research Allows to Reduce the Sample Size by More Than Twice

While planning a clinical study, which utilizes eDiaries, Sponsors often choose between hard copies and digital systems.

In 2016, Smooth Drug Development developed and validated its unique platform for electronic diaries use. It is an application for mobile devices – tablets, smartphones, which enables to collect data, send it to the data-centers, and make it available for doctors and monitors in real time.

In 2016-2017, the Smooth Drug Development team conducted two studies of similar products, with similar designs on the homogenous population of patients. In the first study, the investigators utilized paper diaries (research I, blue graphs below). In the second one, patients were using electronic diaries of the Smooth company (research II, red graphs). All data were blinded and processed in a special way in order to enable conduct of a comparative analysis.

Smooth Drug Development specialists compared the data and made important conclusions, which can influence the choice of patients` data collection methodology.

1. In the study with electronic diaries, dispersion (data spread) was significantly lower. It facilitated faster increase of the test power.

Graph 1 demonstrates the comparison of theoretical (calculated on the basis of all observations) and real (calculated on the basis of observations in each specific time) test power in each study. As one can see, the real power increase and achievement of required 80% in study II progresses faster than the theoretical one. This effect is conditioned by more homogenous data. Data of study I demonstrate greater spread of values and slower reach of required minimum.

Smooth Drug Development published an article on efficacy of electronic diaries in clinical research in Pharmvestnik

2. In the study with electronic diaries, the required test power of 80% was achieved on significantly smaller sample size, which means that the final results of the research could be achieved with engagement of a smaller number of patients.

Graph 2 demonstrates dependency of the sample size, required for the achievement of 80% test power, from the number of enrolled patients. As one can see, the required power in study II is arranged in a narrower corridor, and the maximum meaning of sample size is 67, 5% lower compared to the analogical criterion in graph 1.

Smooth Drug Development published an article on efficacy of electronic diaries in clinical research in Pharmvestnik

3. Data entry and processing in study II with e-diaries took much less time.

Parameter per 1 subject

Study I

Study II

Average time for transferring source information into the database, monitoring, and query resolution

2 h 52 min

22 min

Average amount of queries



Conclusion: this example demonstrates that in clinical studies with design, where primary endpoint evaluation is based on results from data in patients` diaries, utilization of electronic systems gives various advantages and enables achievement of proper test power on a smaller subject population.

Smooth Drug Development biomedical statisticians have vast experience in application of adaptive designs of clinical studies. Taking this into account, one may assume that the above described peculiarities can potentially be used in practice, when calculation of sample size and interim analysis points are based on statistical modelling with consideration of the range of coefficient of variation. This, in its turn, reduces the cost of the clinical study and shortens its duration in comparison with studies with paper diaries.

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