Yes, I'm commenting on yet another prospective cohort study, a great tool to identify issues particularly for rare diseases like pseudotumor cerebri.
Source: Matthews YY, Dean F, Lim MJ, et al. Pseudotumor cerebri syndrome in childhood: incidence, clinical profile and risk factors in a national prospective population-based cohort study. Arch Dis Child. 2017;102(8):715–721; doi: 10.1136/archdischild-2016-312238. See AAP Grand Rounds commentary by Dr. David Urion (subscription required).
This study utilized data gathered from the British Paediatric Surveillance Unit, a prospective cohort data-gathering tool administered by academic pediatric and public health centers in the United Kingdom, with a specific goal of facilitating research on rare childhood diseases. The organization sends out reporting cards ("Orange Cards," shades of Willy Wonka, anyone?) monthly to specialty and subspecialty pediatricians in the UK, asking whether these participants had anything to report on specified diseases. They claim a 94% reporting rate, pretty darn good, so likely the rates and associated factors they report are reasonably reliable.
The authors found 185 cases of pseudotumor cerebri syndrome (PTCS) over a 25-month data collection period, corresponding to an annual incidence of 0.71 per 100,000 population of children ages 1 to 16 years. The highest rate in any subgroup was 10.7/100,000 in obese 12-15-year-old girls. Of course, a cohort study can only show an association, not a cause and effect relationship. Many other studies have suggested a role for obesity in the pathogenesis of PTCS, and when I searched a bit more it seems that most prospective clinical trials for the treatment of PTCS involve weight loss for all groups in the study, with acetazolamide or other medication being the primary intervention of interest. So far, the jury is out as to the optimal treatment of PTCS, with a Cochrane review concluding that we need better trials to come to a more definitive treatment recommendation (how many times have we seen that in the Cochrane Library!). One ongoing randomized controlled trial is comparing bariatric surgery to more traditional weight loss programs and could supply better information on the role of weight loss in treatment.
But what if weight loss is a highly effective treatment for PTCS, perhaps effective 100% of the time? Then, potentially this treatment would lower the rate of PTCS in 12-16-year-old girls from 10.7/100,000 to something closer to the baseline rate of 1.06/100,000. We could then, for fun, calculate a number needed to treat for this intervention; it is a little over 11,000. Translated, 11,000 12-15-year-old girls with obesity and PTCS would need to return to a normal weight in order for 1 additional girl to be cured of her PTCS. That's not a very good return on investment, but of course, we know many other health benefits of weight loss that have a bigger bang for the buck.
