Concomitant medication use and its implications on the hazard pattern in pharmacoepidemiological studies: example of antidepressants, benzodiazepines and fracture risk

Background: Antidepressants and benzodiazepines are often co-prescribed and both associated with an increased fracture risk, albeit with distinctive hazard patterns. Timing of initiation of one with respect to the other and duration of use may influence the combined fracture hazard. The objective of our study was to describe patterns of concomitant use of benzodiazepine and antidepressants in terms of timing of initiation and duration and to illustrate the potential impact of various scenarios of timing of co-use on hip fracture hazard. Methods: Patients initiating antidepressant therapy (2002-2009) were identified from the Netherlands Primary Care Research Database. Concomitant benzodiazepine use was assessed according to the start time of benzodiazepine with respect to antidepressant therapy start. Duration of concomitant use was estimated relative to the length of antidepressant treatment episode.  Results: Among 16,087 incident antidepressant users, 39.0% used benzodiazepines concomitantly during their first antidepressant treatment episode. The time of initiation of benzodiazepine use was variable (64.4% starting before, 13.7% simultaneous and 21.9% after antidepressants). Duration of concomitant use in the three groups varied.  Conclusions: Co-prescribed medications with a common adverse event, may not only require accounting for concomitant use, but also the timing of start and duration of use as the overall hazard may vary accordingly

Co-morbidity and patterns of care in stimulant-treated children with ADHD in the Netherlands

This study aimed at investigating the use of psychosocial interventions and psychotropic co-medication among stimulant-treated children with attention-deficit hyperactivity disorder (ADHD) in relation to the presence of psychiatric co-morbidity. Stimulant users younger than 16 years were identified in 115 pharmacies and a questionnaire was sent to their stimulant prescribing physician. Of 773 questionnaires sent out, 556 were returned and were suitable for analysis (72%). The results are based on 510 questionnaires concerning stimulant-treated children for whom a diagnosis of ADHD was reported. Of the 510 children diagnosed with ADHD, 31% had also received one or more other psychiatric diagnoses, mainly pervasive developmental disorder or oppositional defiant disorder/conduct disorder. We found an association between the presence of co-morbidity and the use of psychosocial interventions for the child (P < 0.001) and the parents (P < 0.001). In the ADHD-only group, 26% did not receive any form of additional interventions, while psychosocial interventions varied from 8 to 18% in children with ADHD and psychiatric co-morbidity. The presence of diagnostic co-morbidity was also associated with the use of psychotropic co-medication (overall, P = 0.012) and antipsychotics (P < 0.001). Stimulant-treated youths with ADHD and psychiatric co-morbidity received more psychosocial interventions and psychotropic co-medication than children with ADHD-only. The type of psychosocial interventions and psychotropic co-medication received by the children and their parents, depended on the specific co-morbid psychiatric disorder being present