Continuing Cannabis Treatment and Answering an Autism Follow-Up Survey Were Different Counts

In an autism cohort summarized by Bilge and Ekici, more patients continued cannabis treatment than completed the outcome questionnaires. Improvement percentages from respondents should not be assigned to every patient who started.

The follow-up populations narrowed

The review describes Bar-Lev Schleider and colleagues’ open-label cohort of 188 patients. After one month, 179 continued treatment, while 119 were evaluated. At six months, 155 continued treatment, but 93 answered the questionnaire. These figures distinguish treatment retention from outcome ascertainment. Continuing to receive a preparation does not ensure that a patient supplied the information used in a reported effectiveness percentage.

A response proportion needs its denominator

The review reports favorable assessments among six-month questionnaire respondents and a higher proportion reporting good quality of life than before treatment. Those observations concern the available follow-up data. They should not be rewritten as the proportion of all 188 starters who demonstrably improved. Patients with missing questionnaires might have had different outcomes, and the reported figures alone do not determine the direction or size of that difference.

Missing follow-up adds to the design limitations

The cohort was open label, used CBD-rich cannabis with THC, and did not supply a randomized placebo comparison. Expectations, other care and differences between respondents and nonrespondents could influence the observed pattern. This does not mean the reported improvements were unreal; it limits the causal and population-wide interpretation. For a research-based claim, give the starting cohort, continuing group and evaluated group before stating an improvement rate. The distinction is especially important when a reassuring retention figure appears beside an efficacy percentage calculated from a substantially smaller set of respondents.

Related analysis: the broader findings and limitations of this research.

Research cited

Source used for this analysis: Bilge and Ekici (2021). CBD-enriched cannabis for autism spectrum disorder: an experience of a single center in Turkey and reviews of the literature. Journal of Cannabis Research.