Impact of parental body mass index at diagnosis on obesity in survivors of pediatric craniopharyngioma.

Objective: It is well known that both genetic background and lifestyle influence the development of 'general' obesity. However, the role of parental body mass index (BMI) on the development of obesity in long-term survivors of childhood-onset craniopharyngioma (CP) is not well understood. This study analyzed the correlation of patients' BMI at diagnosis and last visit and parental BMI at CP diagnosis and further explored potential risk factors for obesity in CP patients.

Design: This is a registry-based retrospective cohort study.

Methods: In total,291 CP patients and their parents recruited in the German KRANIOPHARYNGEOM studies were included. Correlations between patient's BMI SDS at CP diagnosis and last visit and parental BMI at CP diagnosis were analyzed. The associations between hypothalamic damage, maternal/paternal BMI and CP patients' obesity at last visit were analyzed by multivariable logistic regression.

Results: At follow-up, 52% of CP patients developed obesity (BMI > 3SDS). Patient's BMI SDS at last visit was moderately correlated with BMI-SDS at CP diagnosis (r = 0.48, 95% CI: 0.38-0.58, P < 0.001), and also with maternal BMI at diagnosis (r = 0.28, 95% CI: 0.17-0.38, P < 0.001) and paternal BMI at diagnosis (r = 0.3, 95% CI: 0.19-0.41, P < 0.001). However, the contributing role of parental BMI to the pathogenesis of obesity was small compared to the impact of hypothalamic damage.

Conclusion: We conclude that besides hypothalamic damage, parental disposition for obesity is associated with the development of obesity in patients after CP. Our results indicate that also the family situation could have an influence on the development of obesity after CP and might be a therapeutic target.

Significance statement: Survivors of childhood-onset craniopharyngioma are at risk of developing morbid obesity. So far, patients with posterior hypothalamic involvement and lesion were identified as a high risk group. With this study, the influence of parental body mass index on the risk of obesity was investigated. Patient's body-mass-index at last visit was correlated with maternal and paternal body mass index at diagnosis. With increasing maternal or paternal body mass index, the likelihood of obesity in individuals with CP increased. Nevertheless, the parents' weight had only a small effect on the development of patients' obesity compared to hypothalamic damage.