ADHD: diagnosis rate twice as high in the region

2023-04-24 04:00:00

In Quebec, a child living in Bas-St-Laurent is two and a half times more likely to be diagnosed with ADHD than a child living in Montreal. The significant gap between the metropolis and the regions worries experts, who fear a phenomenon of overdiagnosis.

Quebec is the Canadian champion in the consumption of psychostimulants such as Ritalin, drugs used to reduce the symptoms associated with attention deficit disorder with or without hyperactivity (ADHD).

However, a very large study carried out among 795,000 Quebec children shows that the probability of being diagnosed with ADHD varies considerably depending on the region where they live.

In Montreal, this proportion is 11%, while it averages 20% for the other regions. Bas-St-Laurent, Laurentides and Estrie are among the regions where this probability is highest.

These results, compiled from data from the Régie de l’assurance maladie du Québec over a period of ten years, show regional disparities “even higher than what had been reported in the past”, indicates Philip Merrigan, professor in economics at UQAM and researcher at CIRANO, who co-directed this study with Catherine Haeck, Geneviève Lefebvre and Pierre Lefebvre.

«Angle mort»

In a just-published article, the authors say these discrepancies represent a “blind spot” of a concerning phenomenon, which could suggest overdiagnosis depending on the region. However, the authors of the study do not have qualitative data that would allow them to explain the situation with certainty.

“It’s a little curious that we haven’t yet tried to investigate this more precisely, especially since we are already diagnosing more in Quebec. [pour le TDAH] than elsewhere in Canada and even internationally,” says Merrigan. Do so many kids really need ADHD medication?”

The results seem to show “that there are practices in Montreal that make them better able to avoid these diagnoses”, but these practices are obviously “not widespread throughout the province”, notes Catherine Haeck, who is also a professor of economics at UQAM and a researcher at CIRANO.

For its part, the National Institute of Public Health had already argued that the differences between regions could be explained by differences in access to resources in the health system.

The higher proportion of immigrants in Montreal could also weigh in the balance, adds Mr. Merrigan, who wonders in particular if the parents of immigrant origin would be more fearful in relation to the use of medication for their child.

“Class Babies”

This large study also found that the youngest children in their class, born in September, have 35% higher ADHD diagnosis and medication rates than students born in October. In Quebec, the school entry age depends on the child’s age on September 30.

These results, which were first reported by The Press in January, suggest a “high likelihood of overdiagnosis and overtreatment of ADHD,” according to the study authors.

Immature behaviors in class, related to the age of the children, could then have been confused with symptoms associated with ADHD, indicate the researchers.

Diagnosis from 6 years old

Their work also shows that the majority of children receive their first diagnosis of ADHD between the ages of 6 and 8, which is followed in most cases by taking medication.

“Everything is therefore played in primary school,” write the authors of the study. The latter consider that it “could be desirable to delay the moment of a diagnosis with taking medication” in order to consider this type of solution “only for a minority of children who really cannot function in class”.

In 2019, a group of pediatricians denounced the too easy recourse to drugs to treat the symptoms associated with ADHD in young people, this rate being three times higher in Quebec than in the rest of Canada.

Their open letter, first published in The newspaper, caused a stir and led to a parliamentary committee on the subject.

In a report made public in 2020, the commission recommended reviewing the practices surrounding the diagnosis of ADHD, to reduce the risk of overdiagnosis. ADHD and children

Probability of receiving at least one diagnosis of ADHD in children by region

  • Lower St. Lawrence: 26,5 %
  • Laurentians: 25 %
  • Estrie: 24 %
  • Lanaudiere: 23,5 %
  • Saguenay-Lac-Saint-Jean: 23 %
  • Gaspésie-Îles-de-la-Madeleine: 21,5 %
  • National Capital: 20 %
  • North Coast : 20 %
  • Northern Quebec: 20 %
  • Monteregie: 20 %
  • Mauricie and Centre-du-Québec: 19 %
  • Chaudiere-Appalaches: 19 %
  • Outaouais : 17,5 %
  • Abitibi-Témiscamingue: 16 %
  • Laval : 14 %
  • Montréal : 11 %
  • Total other regions excluding Montreal: 20 %

Source: Effects of months and dates of birth on attention-hyperactivity diagnoses and ADHD medication in Quebec, 2000-2018, study by Catherine Haeck, Geneviève Lefebvre, Pierre Lefebvre and Philip Merrigan.

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