Influence of Naltrexone/Bupropion Combination Treatment on Body Mass Index in Prader–Willi Syndrome Re: “Prader–Willi Syndrome,Management of Impulsivity,and Hyperphagia in an Adolescent” by Puri et al. (J Child Adolesc Psychopharmacol 26:403–404,2016)

To the Editor:

We read with interest the case report by Puri et al. (2016) describing a 13-year-old girl with Prader–Willi syndrome (PWS) treated for 6 weeks with a naltrexone/bupropion combination (Contrave) to target impulsivity, inattention, physical aggression, and overeating behavior (Puri et al. 2016). The latter symptom, along with morbid obesity, is a hallmark of PWS, and has been the subject of numerous attempts to find a successful pharmacotherapeutic solution. A drug that showed promise in alleviating hyperphagia and obesity in PWS could potentially be hugely beneficial to this patient group.

Puri et al. (2016) report seemingly positive findings in this study—namely improved eating habits and a difference between body mass index (BMI) pretreatment and posttreatment with Contrave—and recommend a longer term clinical trial of this drug in PWS. Unfortunately, however, the improved BMI in this patient appears merely to be an artifact of a calculation error or an error in converting values between the imperial and metric systems. BMI values are given as 33.9 kg/m² at baseline and 32.7 kg/m² after 6 weeks' treatment, based on weight and height values of 162.1 lb and 148.5 cm (baseline) and 161.7 lb and 148.6 cm (posttreatment). According to our calculations, these raw values equate to an initial BMI of 33.3 and posttreatment BMI of 33.2, a far smaller difference than that reported.

Although BMI is an important metric in the assessment of the efficacy of potentially appetite-regulating drugs, care must be taken to avoid reporting incorrect information and giving false hope to PWS families. This is even more important given the already scant literature—especially for a novel agent—in weight management in PWS.