Summary
This study found that from 2000 to 2021 the prevalence and incidence of anxiety in Flemish primary care increased steeply, but mostly over the past 5 years. The younger age groups seem to be responsible for most of this increase. The number of comorbidities in patients with anxiety rose significantly during the study period. Medication prescription among patients with anxiety also increased, most notably for SSRIs.
Strengths and limitations
The major strength of this study is the inclusion of longitudinal data, reflecting the registration trends of anxiety as they developed during the 22-year study period. Access to prescription and comorbidity data allowed for a balanced and multifaceted view on anxiety as it presents to GPs in Flanders. Given the paucity of real-world data on anxiety in primary care, the authors believe the current study is a valuable addition to the evidence. The study also comes with some limitations. The denominator of the study population can vary because of the fact that patients in Belgium are not registered with a particular GP. Although only 40% of the population go to see one GP only, the Usual Provider Continuity Index still remains acceptable (>75% of consultations with a specific GP for >65% of the Belgian population).23 Data for patients going to a GP outside of the INTEGO network, however, are not included.
The YCG also does not capture the whole practice population, but only the patients who visit at least once a year. It is, however, the most realistic approach in Belgium. The authors do not know whether GPs over- or underdiagnosed anxiety in their patients, and what clinical tools they used to arrive at their diagnosis. Also, there might exist regional variations in coding practice (for example, some practices are more likely to code anxiety as a symptom and not a diagnosis), something which this study did not specifically investigate. Diagnoses detailed as free text were not included in this study.
Many patients with anxiety problems might not go to their GP, leading to an underestimation of the real disease burden. The effect of the COVID-19 pandemic on anxiety was not specifically evaluated. Medication could have been prescribed for other indications than anxiety (for example, SSRIs for depression). The uptake of psychotherapy among patients could not be studied, because it is not registered in the database used.
Comparison with existing literature
Trends in the prevalence and incidence of anxiety.
The recent increase in the registration of anxiety in this study corresponds to the international literature. Although methodologically different, recent increases have been seen in young people across multiple studies in different countries.24–26 This may be because of actual disease burden or an increased acceptance and awareness of mental disorders in general, leading to earlier recognition. Some studies point in the direction of the latter.27,28 Other authors blame the emergence and importance of social media in the lives of young adults.29
From the data in the current study it is unclear whether the increase in the registration of anxiety is actual or perceived. Of note is that the current study used the ICPC-2 code P74, which is a clinical diagnosis. GPs might be hesitant to diagnose a disorder based solely on subclinical symptoms, which is why in some studies there seems to be a recent tendency to code anxiety symptoms rather than diagnoses.25,30 This might also explain why the registered prevalence and incidence of anxiety in the current study are decidedly lower than in other similar studies.14,25,31 Furthermore, as stated in a previous article by the same team, this increase might also partly be brought about by a registration effect.19 This is a form of bias: anxiety could be more likely to be registered now than earlier in the study period for various reasons (for example, more diligent and more frequent coding and registration).
The final 2 years of the study period were marked by the ongoing COVID-19 pandemic, during which mental health disorders, particularly anxiety, seemed on the increase.32,33 The current results show an increasing incidence and prevalence for anxiety in those years, but a COVID-19-specific analysis was not performed. The Belgian public health institute Sciensano found that self-reported mental health in Belgium fluctuated during the pandemic depending on the specific phase (restrictions versus relaxation of measures).34 It is conceivable that many patients did not seek help for anxiety during the first waves of the pandemic, making figures in the current study likely underestimates.
For the calculations in the current study it was assumed anxiety disorder was chronic, a stance shared by other authors as well.35 A sensitivity analysis was also conducted using a 1-year contact-free interval and the conclusions remain robust. Using this much shorter period a lower prevalence was arrived at, which is mathematically evident (see Supplementary Table S2). The trends were largely conserved (see Supplementary Figure S2).
Trends in comorbidities.
The most salient finding here was the fact that the average number of chronic diseases for each patient increased significantly. This is in line with previous findings from the same author group concerning depression.19 Patients presenting with mental health disorders in primary care tend to become more complex over time. However, it is also possible that GPs’ awareness of anxiety might be increased specifically in patients with comorbidities.
In any case, a multidisciplinary approach to these patients is warranted. The GP is perfectly placed to coordinate care between first- and second-line health professionals. In an analysis by Martín-Merino et al, patients with anxiety were more likely to misuse alcohol, have chronic obstructive pulmonary disease (COPD) or cancer, or be admitted to hospital or referred for another health problem.31 In the current sample, there was no concurrent trend for alcohol misuse, although anxiety was significantly associated with a number of somatic conditions, such as asthma and COPD, cardiovascular problems, and cancer.
The strong association with depression is not new and controversy exists as to whether the presence of anxiety might predict the onset of depression or vice versa,15 or even whether they constitute different syndromes altogether.13,14
Trends in medication.
In the prevalent anxiety case group, the relative amount of psychoactive medication prescriptions increased, albeit only significantly so for the final 6 years. This is consistent with a study by Noordam et al, who also found an increase in prescriptions for mental health disorders.36 Female patients with anxiety in the current study received proportionally more prescriptions than males, which was the case in the Noordam et al, study as well.36 Chronic use, which was defined in the current study as ≥3 prescriptions per year, increased significantly, whereas occasional use (one prescription per year) declined. For benzodiazepines specifically, the definition of chronic use in international literature tends to vary and is rarely uniform across studies.37
The most frequently prescribed medications in the current study were SSRIs, anxiolytics, and hypnotics. Initially, anxiolytics were prescribed more than SSRIs but the two switched positions around 2017. SSRIs are also a first-line treatment for depression, and the important comorbidity between anxiety and depression might also have been a driving force. According to the National Institute for Health and Care Excellence guidelines, the recommended treatment for anxiety disorder, besides psychotherapy, is SSRIs followed by serotonin–noradrenaline reuptake inhibitors.38 The use of benzodiazepines is explicitly discouraged, except for short-term crisis management. This might also have contributed to the prescription trends seen in the data in the current study.
Another interesting trend is the recent steep increase of prescriptions (such as trazodone) in the neuromodulator group.
Implications for practice
In this registry-based study, a significantly increasing prevalence and incidence of physician-registered anxiety was found, particularly in the past 5 years and in the youngest age groups. Patients with anxiety tend to become more complex or patients with multimorbidity are at least more easily diagnosed with anxiety. A holistic, multidisciplinary primary care approach for these patients, with the GP taking on a coordinating role, is important.
Without knowing about referrals for psychotherapy, treatment for anxiety in Belgian primary care seems to be heavily dependent on medication. In any case, there has been more adherence to official guidelines recently with the use of SSRIs increasing and the use of anxiolytics declining.
