Objectives：MID-NET® has contributed to post-marketing drug safety assessment through various pharmacoepidemiological studies. To further promote an appropriate use of MID-NET®, this paper describes points to consider in conducting studies utilizing MID-NET® based on results from the two MID-NET® studies.Study design：Cohort study based on the secondary utilization of medical information databaseMethods：In the first study, the incidence of decreased liver function in patients prescribed drugs for pulmonary arterial hypertension was compared with the results from all-case surveillance (primary data collection). In the second study, real world utilization of biosimilar (hereinafter referred to as “BS”) was investigated to understand characteristics of BS prescription in clinical practice. Results：Although the incidence of decreased liver function varied depending on outcome definitions, the proportion on the definition identifying severe cases was similar to that in the all-case surveillance. It suggests that use of multiple outcomes including a definition taking into consideration a degree of severity is important to evaluate study results with robustness appropriately. In the second study, increased trends of BS prescriptions and various patterns of switching (from original biopharmaceutical to BS or from BS to original biopharmaceutical) depending on age and other factors were confirmed. It indicates that considerations about real world utilization of original biopharmaceutical and BS are necessary for future studies targeting BS.Conclusion：These studies further expanded an understanding and knowledge about data characteristics of MID-NET® and provide useful points to consider for promoting appropriate data utilization in future MID-NET® studies.

OBJECTIVE: This study estimated the effects of weekend and off-hour childbirth and the size of perinatal medical care center on the incidence of cerebral palsy. METHODS: The cases were all children with severe cerebral palsy born in Japan from 2009 to 2012 whose data were stored at the Japan Obstetric Compensation System for Cerebral Palsy database, a nationally representative database. The inclusion criteria were the following: neonates born between January 2009 and December 2012 who had a birth weight of at least 2000 g and gestational age of at least 33 weeks and who had severe disability resulting from cerebral palsy independent of congenital causes or factors during the neonatal period or thereafter. Study participants were restricted to singletons and controls without report of death, scheduled cesarean section, or ambulance transportation. The controls were newborns, randomly selected by year and type of delivery (normal spontaneous delivery without cesarean section and emergency cesarean section) using a 1:10 case to control ratio sampled from the nationwide Japan Society of Obstetrics and Gynecology database. RESULTS: A total of 90 cerebral palsy cases and 900 controls having normal spontaneous delivery without cesarean section were selected, as were 92 cerebral palsy cases and 920 controls with emergent cesarean section. A significantly higher risk for cerebral palsy was found among cases that underwent emergent cesarean section on weekends (odds ratio [OR] 1.72, 95% confidence interval [CI] 1.06-2.81) and during the night shift (OR 2.29, 95% CI 1.30-4.02). No significant risk was found among normal spontaneous deliveries on weekends (OR 1.63, 95% CI 0.97-2.73) or during the quasi-night shift (OR 1.26, 95% CI 0.70-2.27). Regional perinatal care centers showed significantly higher risk for cerebral palsy in both emergent cesarean section (OR 2.35, 95% CI 1.47-3.77) and normal spontaneous delivery (OR 2.92, 95% CI 1.76-4.84). CONCLUSION Labor on weekends, during the night shift, and at regional perinatal medical care centers was associated with significantly elevated risk for cerebral palsy in emergency cesarean section.
Case-Control Studies ; Cerebral Palsy ; epidemiology ; etiology ; Delivery, Obstetric ; statistics & numerical data ; Health Facilities ; statistics & numerical data ; Humans ; Incidence ; Infant, Newborn ; Japan ; epidemiology ; Parturition ; Perinatal Care ; statistics & numerical data ; Retrospective Studies ; Time Factors