During 1993-2004, the number of UK patients newly-diagnosed with depression declined by nearly 25%, but numbers of prescriptions written for antidepressants nearly doubled in the same period, says a new study.

This dramatic rise is due to a year-on-year increase in the number of people taking antidepressants on a long-term basis, researchers from the University of Southampton conclude, in a study published the British Medical Journal (BMJ) on October 23.

The researchers extracted data on all new incident cases of depression from the general practice research database (GPRD) between 1993 and 2005 and, analysing data from the 170 practices that contributed for the full duration of the study, they found that a total of 189,851 people experienced their first episode of depression between 1993 and 2005, of which 150,825 (79.4%) received a prescription for antidepressants in the first year of diagnosis. This proportion remained stable across all the years examined.

The overall incidence of new cases increased in young women but fell slightly in other groups, such that overall incidence increased then declined slightly; men - 7.83 cases per 1,000 patient years in 1993 to 5.97 in 2005; women - 15.83 cases per 1,000 patient years in 1993 to 10.06 in 2005. However, antidepressant prescribing nearly doubled during the period, the average number of prescriptions issued per patient rising from 2.8 in 1993 to 5.6 in 2004, and the majority were given as long-term treatment or as intermittent treatment to patients with multiple episodes of depression.

According to data from the NHS Prescription Services (NHS RxS), more than 30 million prescriptions for selective serotonin reuptake inhibitors (SSRIs) including Eli Lilly’s Prozac (fluoxetine) and GlaxoSmithKline’s Seroxat (paroxetine), are now issued per year, twice as many as the early 1990s, and the researchers found that 90% of people diagnosed with depression are now taking SSRIs either continuously or as repeated courses over several years.__

“We estimate that more than two million people are now taking antidepressants long-term over several years, in particular women aged between 18 and 30,” said the study’s leader Tony Kendrick, professor of primary medical care at the University’s School of Medicine.

Moreover, he noted the team’s previous research had found that while these drugs are claimed not to be addictive, many patients had in fact found it difficult to come off them, due to withdrawal symptoms such as anxiety, and many wanted more help from their general practitioner (GP) to come off the drugs.

“We don’t know how many really need them and whether long-term use is harmful. This has similarities to the situation with Valium in the past,” said Prof Kendrick.

Commenting on their findings, the researchers conclude that, while previous clinical guidelines have focused on antidepressant initiation and appropriate targeting of antidepressants, future research and guidance should, in order to address the costly rise in prescribing of these drugs, concentrate on appropriate long-term prescribing for depression and regular review of medication.