- A number of South African news outlets have published the statistic that one in four South African workers have been diagnosed with depression, usually attributing it to the South African Depression and Anxiety Group (SADAG).
- The study SADAG refers to was done by a health and economic research organisation, and only included employees who worked in advertising or market research. One in four in this limited sample said they had been diagnosed with depression by a professional.
- Experts pointed out a number of problems with the study, primarily that it cannot be generalised to the South African workforce as a whole.
“At least one in four employees are diagnosed with depression,” said an article published in early July on Fin24, a South African business news website.
Other South African publications like Forbes Africa, Huffington Post and Dispatch Live have also repeated this statistic in recent years.
Is there truth to it?
Survey very limited
The Fin24 article credited a factsheet by the South African Depression and Anxiety Group (SADAG) as its source. The group’s operations director Cassey Chambers told Africa Check that the information was from a research study done by Hexor, a health and economic research organisation now known as TCD Global.
“We were involved in disseminating the information and creating awareness around it, [but] SADAG didn’t actually host this research ourselves,” Chambers said.
The study, which was published in 2016, was based on an online survey. One of the study’s authors and TCD Global’s pharmacoeconomic and data analytics manager, Margreet de Necker, told Africa Check that the participants were recruited through a South African online market research panel in June 2014.
“We used a sample of 1,061 employees who worked in advertising or market research and were employed full or part-time or at some time during the 12 months prior to the survey,” she said.
Of the people surveyed, 278 answered yes to the question “Have you ever personally been diagnosed as having depression by a doctor/medical professional?”
De Necker added: “This indicates 26.2%, which can be interpreted as one in four participants in the study.”
But the authors highlighted several limitations, including that it was a self-reported survey.
“The results from this study all rely on subjective responses to an online questionnaire. Anonymity supports the reliability of the data, however, the design of this study does not allow for diagnosis of depression to be verified.”
‘Basically no way study can be generalised’
Dr Andrew Kerr is chief research officer at DataFirst, a research data service based at the University of Cape Town (UCT) where he teaches a course titled “Analysis of Survey Data”. He believes the study’s methodology was of low quality.
“The survey was done online, so [it] excludes anyone without internet access, which is a large fraction of employees. These types of employees could be more or less likely to be depressed, we don’t know.”
Another selection problem, Kerr said, is that all of the participants worked in the advertising or market research sector. The study also did not report non-response rates, or the fraction of people who were asked to respond to the survey but did not.
“Again, those with depression may be more or less likely to respond, we don’t know,” Kerr said. “These could all affect the estimated proportion of employees with depression.”
(Note: De Necker said to ask the research agency responsible for collecting the data, Ipsos MORI, about the non-response rate of the study. The agency has not responded to our request for comment. We will update this report if they do.)
“There is basically no way their study can be generalised to any population, either all employees or even all advertising or market research employees [in South Africa],” he said.
Only one representative study on mental disorders
The head of UCT’s psychiatry and mental health department, Prof Dan Stein, told Africa Check there has only been one nationally representative study on mental disorders, the South African Stress and Health (SASH) study.
It surveyed a representative sample of 4,351 adults between 2003 and 2004 and found that close to 10% of the respondents had suffered from major depressive disorder at some point in their life. Almost 5% had suffered from the disease in the course of the previous 12 months.
Stein, who co-authored the study, said that “the data were analysed as a whole though, [and] we didn’t focus on just people who were employed”.
Janine Roos, director of the Mental Health Information Centre of Southern Africa, also said the SASH survey was the only nationally representative study on mental disorders she was aware of.
Roos added that when talking about mental disorders, the term prevalence rate (the proportion of people affected by a disease) must be used with caution, because of the lack of nationally representative data.
“[We must do] good epidemiological and representative research with a sound research methodology, otherwise there is the danger of false and inflated prevalence rates.”
Conclusion: No study backs up claim that 1 in 4 South African employees have depression
Since 2015, many journalists have cited a statistic that one in four South African employees are diagnosed with depression. Though the South African Depression and Anxiety Group is usually quoted as the source, the organisation told Africa Check they only helped to spread another organisation’s findings.
The statistic is based on a 2014 online survey of 1,061 employees who worked in advertising or market research. Just over a quarter (26.2%) of the respondents claimed that they had been diagnosed with depression by a medical professional in the 12 months before the poll.
Experts told Africa Check that various flaws in the study’s methodology mean that the findings cannot be generalised to all South African employees.
We therefore rate the claim as unproven.
Sethu Mbuli is a journalism honours student at Stellenbosch University and also holds a BSc in chemistry, ocean and atmosphere science from the University of Cape Town.