Prevalence and health repercussions of depression

According to the World Health Organization (WHO), depression affects about 121 million people in the world, and less than 25% of them have access to effective treatments. It warns that one out of every five people will develop depressive symptoms in their lifetime, and this number increases if there are other concurrent factors, such as medical illnesses or stressful situation¹. Moreover, it is expected that in 2020, depression will become the second most common cause of disability, after cardiovascular diseases^2.

The prevalence of the illness varies according to the studied country. The American National Comorbidity Survey Replication observed that 16.2% of people showed a major depressive disorder at some point in their lives (lifetime prevalence) and that 6.6% showed it in the last 12 months (one-year prevalence)³, while the Green Book produced by the Commission of the European Communities estimates that the annual prevalence in the European population of 18 to 65 year-olds is 6.1%⁴.

An epidemiological study performed on a representative sample of the population observed a lifetime prevalence of mental disorders of 19% and a one-year prevalence of 8.4%, and it revealed that the major depressive episode is the most frequent mental disorder, with a lifetime prevalence of 10.5% and a one-year prevalence of 3.9%5. However, among hospitalised patients, the prevalence of depression increases to 18.9%6, and some groups, such as illegal immigrants, are especially sensitive to it, with a percentage of 40.7%⁷.

In the WHO’s opinion, suicide constitutes a major public health problem (to a large extent preventable), and it translates into almost one million victims per year, in addition to very high economic costs. In Spain, the number of suicides committed has increased in recent years, going from 1652 in 1980 (1237 men and 415 women) to 3399 in 2005 (2570 men and 829 women). The suicide mortality rate in the last year was 15.79/100,000 in habitants (12.03/100,000 in men and 3.76/100,000 in women), and important differences are observed when taking into account the age group in which suicide occurs: 12.48 at 25-29 years; 17.43 at 50-54 years; 31.68 at 70-74 years; 49.45 at 80-84 years; and 79.96 at 90-94 years⁸.

According to the Ministry of Health and Consumer Affairs, in 2005 the expense on antidepressants exceeded 600 million Euros, 6 times higher than in 1994. By number of containers, selective serotonin reuptake inhibitors (SSRIs) represented 69.5%, versus 30.5% for other antidepressants. The variation of SSRIs with respect to 2004 was +1.07% by number of containers and –0.36% by cost, versus an 11.39% increase in the use of other antidepressants (the majority, new molecules) by number of containers and 6.33% by cost⁹.

On average, patients with depression lose 11 days for every 6-month period, while individuals without this condition only lose two or three days¹⁰.

Due to its high prevalence, the cost of its treatment, its role as one of the main risk factors of suicide (about fifty-eight thousand people commit suicide each year in the European Union, a figure that exceeds that for annual deaths due to traffic accidents, homicides or HIV/AIDS) and its impact on personal productivity, depression plays a huge economic role, not only in the health system but also in society.

Variability of clinical practice

The 14.7% of patients who go to primary care consultations for any reason show depression but only 72% of those patients are diagnosed, and 34% receive treatment with antidepressants¹¹. Detection is positively associated with the level of education, the severity of the symptoms, the degree of disability and the complaint of explicitly psychological symptoms, while treatment with antidepressants is associated with the civil status, the severity of the depression, the frequency of visits to the primary care physician and the complaint of psychological symptoms¹². Thus, a considerable percentage of patients with depression is not recognised, and many of those who are recognised do not receive suitable treatment^11-13. Both the detection rates and the treatment rates are greater in the more severe forms of depression¹², and moreover, up to 26.5% of patients diagnosed with depression by the family physician do not meet the formal criteria for this diagnosis¹⁴.

A recent study by the Atlas de Variaciones en la Práctica Médica¹⁵ examines, in 156 health areas of 15 Autonomous Communities, the admissions due to psychiatric conditions in acute hospitals of the public network of the National Health System during 2003 and 2004. The results show that affective psychoses, which include major depression, presented in Spain a standardised rate of hospital admissions per 10,000 inhabitants between 0.09 (the lowest health area) and 12.52 (the highest health area), while in Galicia this variability is smaller, varying between 1.65 and 4.37.

In general, there is a high variability in the management of depression¹⁶, which has been demonstrated among primary care professionals in the various rates of referral, average duration of visits, attitude towards a lack of therapeutic response and follow-up on patients with depression¹⁷.