Elsevier

Psychiatry Research

Volume 244, 30 October 2016, Pages 382-387
Psychiatry Research

Gender ratios of administrative prevalence and incidence of attention-deficit/hyperactivity disorder (ADHD) across the lifespan: A nationwide population-based study in Taiwan

https://doi.org/10.1016/j.psychres.2016.08.023Get rights and content

Highlights

  • Performance of the lifetime ADHD prevalence using claimed population database.

  • Performance of the lifetime ADHD incidence using claimed population database.

  • Performance of the gender ratio of diagnosed prevalence and incidence in ADHD.

  • The male-to-female ratio of healthcare-seeking adults with ADHD is diminished.

  • Compared to child or adolescent, the gender ratio of ADHD is reversed in adults.

Abstract

To verify the hypothesis that there is different gender ratio of attention-deficit/hyperactivity disorder (ADHD) among adults compared to children and adolescents in the clinical setting among Asian population. The nationwide population-based database containing data on enrollees in the National Health Insurance program in Taiwan during 2000–2007 was used in this study, and we investigated the lifetime gender ratios of administrative prevalence and incidence in healthcare-seeking ADHD patients (n=228,029). The male-to-female ratios of diagnosed incidence and prevalence of child/adolescent ADHD (age <20 years) ranged from 3.39 to 4.07 and 3.87–4.31, respectively. The male-to-female ratios of diagnosed incidence and prevalence of ADHD in the adult group (age 20–65 years) ranged from 0.24 to 0.76 and 0.35–0.98, respectively. In conclusion, there was substantially increased female-to-male ratio in adults ADHD compared to children and adolescents in the clinical setting. Further researches on the management and mechanism are needed.

Introduction

Attention-deficit/hyperactivity disorder (ADHD) affects school-aged children about 3–12% (Faraone et al., 2003, Gau et al., 2005, Polanczyk et al., 2007, Wang et al., 1993, Willcutt, 2012) and adults approximately 3–5% (Fayyad et al., 2007, Kessler et al., 2006, Simon et al., 2009). In addition to the shift in conceptualization of ADHD as a disorder often persisting into adulthood (Faraone et al., 2000b, Wender et al., 2001), there has been an increasing body of research that has argued that ADHD is not a male-dominant disorder (Nussbaum, 2012, Quinn, 2008, Rucklidge, 2010). Epidemiology data indicate that the gender ratios of males to females in ADHD children were from 2:1 to 9:1 in clinical subjects and 2:1 to 3:1 in community samples (Arcia and Conners, 1998, Bruchmuller et al., 2012, Huss et al., 2008). However, the concept that ADHD is a male-dominant disorder may due to that most studies focus on groups among children and adolescents (Hodgkins et al., 2011, Winterstein et al., 2008), rather than adults. Several studies examining gender differences in ADHD patients indicated that the discrepancy in prevalence rates may lessen in adults (Almeida Montes et al., 2007, Arcia and Conners, 1998, Biederman et al., 1994, Faraone et al., 2000a). In addition, other studies revealed that the adults have a similar percentage of patients diagnosed with ADHD between males and females (Biederman et al., 1994, Faraone et al., 2000a). It has been reported a considerable increase in the number of healthcare-seeking adult females for attention problem (Arcia and Conners, 1998). Moreover, Almeida Montes et al. (2007) found an even higher prevalence of ADHD among women than men in a psychiatric out patient service, although the sample size was limited in that study.

In Taiwan, the estimated overall prevalence rate of ADHD among primary school children was found to be 9.9% (Wang et al., 1993), while the rate in boys (14.9%) was 3.3 times higher than in girls (4.5%). The prevalence rate of ADHD among seventh-to ninth-grade adolescents ranged from 7.5 to 3.3% (Gau et al., 2005), with boy-to-girl odd ratios of 4.5-5.2. In our previous study using claims data from among Taiwan's National Health Insurance enrollees (Huang et al., 2014), we found that the administrative prevalence of ADHD was still lower than data from the community survey, in spite of an increasing number of patients with ADHD sought medical help. Furthermore, ADHD patients who aged after 13–18 show the substantially decreased incidence and prevalence in treatment.

Available data suggest that the higher diagnosed prevalence among females may be related to previously under-identified ADHD in their childhood (Nussbaum, 2012, Quinn, 2008, Rucklidge, 2010). However, no reliable figures on women with ADHD or the true male-to-female ratio of adults with ADHD exist due to limited data and small sample sizes even though there is evidence that women represent a more significant proportion of adults with ADHD than men (Huang et al., 2014, Nussbaum, 2012, Quinn, 2008, Rucklidge, 2010). Moreover, the majority of previous studies on gender ratio in ADHD have been done in North America and Europe and the figure in Asian population is still unknown. To help fill this gap in the literature, we designed a study to investigate the lifetime gender ratios of prevalence and incidence in administrative ADHD. Using a nationwide population-based database containing data on enrollees in the National Health Insurance program in Taiwan, our objective was to verify the hypothesis that there is different gender ratio of ADHD in adults compared to children and adolescents in the clinical setting.

Section snippets

Data source

This study used Taiwan's National Health Insurance Research Database (NHIRD), a claims database of the National Health Insurance (NHI) program in Taiwan, which covers 99% of the residents of Taiwan. The NHIRD is managed by the National Health Research Institute (NHRI) and has been used in many health-related studies (Chen et al., 2011). All registration records of diseases in the NHIRD database contain one primary diagnosis and up to four secondary diagnoses, using the International

Results

A total of 228,029 patients' records (81.2% males) were enrolled in the diagnosed ADHD cohort during the 8-year study. The 1863 inpatients and 107,903 outpatients were included in our study with males for 1452 (77.94%) and 83,563 (77.44%), respectively. ADHD patients who aged at 20–65 were most diagnosed in hospitalization than outpatients (13.31% vs. 3.99%). The trends of overall incidence rate and prevalence rate of diagnosed ADHD during 2000–2007 are shown in Fig. 1. There was a significant

Discussion

The current study aims to investigate the gender ratios of prevalence and incidence of administrative ADHD in the lifetime, using representative data from Taiwan's NHIRD with a long observation period. The results of this study suggest a trend toward increased prevalence and incidence rates of diagnosed ADHD in Taiwan for both males and females throughout the study period. These findings are similar with the results from other western countries (Hodgkins et al., 2011, McCarthy et al., 2012,

Acknowledgment

This study is based in part on data from the National Health Insurance Research Database provided by the National Health Insurance Administration, Ministry of Health and Welfare and managed by the National Health Research Institutes. The interpretation and conclusions contained herein do not represent those of the National Health Insurance Administration, the Ministry of Health and Welfare or the National Health Research Institutes. We would also like to acknowledge Mr. James Ascencio for his

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