News that sexual harassment in the workplace can cause depression and work absence has hit the headlines after the results of a Danish study were published.

Researchers surveyed 7,603 employees from 1,041 organisations in Denmark, and asked them about symptoms of depression and whether they’d been subjected to sexual harassment from colleagues or customers or clients in the past 12 months. Overall, 4% of women and 0.3% of men reported harassment.

People who reported harassment from customers or clients scored 2.05 points higher on a 50-point depression score than those reporting no harassment. People reporting harassment from colleagues scored 2.45 points higher.

The findings generally support the understanding that sexual harassment can have harmful effects on mental health – regardless of who it comes from.

But this study has many limitations:

The one-off assessment can’t show that harassment preceded depression symptoms.

We don’t know how meaningful the small score difference was and who’d actually diagnosed the employees with depression.

The prevalence of harassment may be inaccurate – people being harassed may not have felt comfortable reporting this, or may not have completed the work survey at all.

This study can only show a link between sexual harassment and depression. It can’t prove that sexual harassment causes depression, no matter how plausible it seems.

Where does the study come from?

The study was conducted by researchers from the National Research Centre for the Working Environment, the University of Southern Denmark and the University of Copenhagen, all in Denmark.

No sources of funding were reported and the authors declared no conflicts of interest.

The study was published in the peer-reviewed journal BMC Public Health, and is available to read free online.

The media generally reported the study’s findings accurately, but the news stories could benefit from addressing the many limitations of what we can conclude from the results of this research.

What kind of research was this?

This cross-sectional study looked at the relationship between employees reporting having been sexually harassed by clients or customers, or workplace colleagues, and symptoms of depression.

Previous research has shown that sexual harassment can have harmful effects on mental health, including depression and anxiety.

Most past research is said to have focused on harassment in the workplace coming from colleagues or supervisors, with little attention given to clients or customers. This was therefore the specific focus of this study.

But the main limitation of the design of this study is that because it’s a one-off assessment, it can’t prove the harassment preceded the depression and is the single direct cause of these symptoms, however plausible that might be. It can only show a link.

What did the researchers do?

The study obtained data from two sources: the Work Environment and Health in Denmark cohort study (WEHD) and the Work Environment Activities in Danish Workplaces Study (WEADW).

The WEHD invites a random sample of employed adults (aged 18 to 64) to take part in a postal or internet-based questionnaire on their health and work environment every two years.

The current study involves 7,603 people who responded in 2012 (covering 1,041 work organisations). They represent half of all people invited to participate in the surveys.

The WEADW invited individual organisations and their employees to take part in the survey.

The study included 1,053 organisations and 8,409 employees within these organisations. Again, these represented about half of the organisations and half of the employees invited to take part.

Sexual harassment in the workplace was assessed by asking: “Have you been exposed to sexual harassment at your workplace during the last 12 months?”. People who responded yes were then asked who the perpetrator was.

The researchers grouped the responses as harassment from clients or customers, or from others in the workplace like colleagues, supervisors or subordinates.

Depression symptoms were assessed using the Major Depression Inventory (MDI), which includes 12 questions that cover the standard diagnostic criteria for depression.

The final score ranges from 0 to 50, with a higher score showing more symptoms of depression.

The researchers split responses into probable depression or not, using a cut-off of above or below 20, which was established in prior research.

They also asked if there were psychological workplace initiatives, such as health insurance to cover treatment by psychologists, or whether the workplace performed a psychosocial assessment.

The researchers looked at the relationship between these factors, adjusting for age, gender and the nature of the workplace (for example, healthcare, industry or construction) as potential confounders.

The final sample from the two surveys combined included 7,603 adults who completed all relevant questions, from 1,041 organisations.

What were the basic results?

The average age of participants was 46. Healthcare work was the most common occupational group (29%), closely followed by “knowledge work” (25%), then industry and the private sector.

The proportion of people who reported sexual harassment was low: 4.1% of women, 0.3% of men, or 2.4% of respondents overall.

People working in health or care were most likely to report sexual harassment from clients or customers, rather than colleagues.

Average depression scores were 2.05 points higher (95% confidence interval [CI] 0.98 to 3.12) for people exposed to sexual harassment from clients or customers compared with those reporting no sexual harassment.

Depression scores were 2.45 points higher (95% CI 0.57 to 4.34) when people had been sexually harassed by their colleagues.

The risk of what the researchers called “clinical depression” wasn’t significantly higher for people exposed to harassment from clients or customers. The risk of “clinical depression” was significant when people were harassed by their colleagues.

But the researchers didn’t define what they meant by “clinical depression”.

Any psychological workplace initiatives reported had no effect on the links between sexual harassment and depression.

What do the researchers conclude?

The researchers concluded: “The association between sexual harassment and depressive symptoms differed for employees harassed by clients or customers and those harassed by colleagues, supervisors or subordinates.

“The results underline the importance of investigating sexual harassment from clients or customers and sexual harassment by colleagues, supervisors or subordinates as distinct types of harassment.

“We found no modification of the association between sexual harassment by clients or customers and depressive symptoms by any of the examined psychosocial workplace initiatives.”

Conclusions

This study in general supports the understanding that sexual harassment can have harmful effects on mental health – regardless of whether it comes from clients or colleagues.

It’s also perhaps unsurprising that health or care workers were more likely to report sexual harassment from clients or customers, as they generally have more close interaction with members of the public than many other professions.

The researchers also pointed out that sexual harassment by clients or customers should not be normalised or ignored by employers.

This study has advantages in its large sample size and thorough assessments, and will provide a valuable contribution to research in this area.

But as a piece of evidence, it still can’t prove that sexual harassment directly causes depression, no matter how likely this may seem.

The study had many limitations, including:

This is a cross-sectional assessment, and participants were asked about symptoms of depression at the same time as they were questioned about harassment. It’s not possible to determine the direction of the relationship and know whether harassment preceded depression symptoms.

The people involved aren’t necessarily representative of all employees. Only half of eligible employees responded to the two surveys in the study. There may be differences in those who chose to respond and those who did not. People who are being harassed in their workplace may be less likely to want to complete a survey on their workplace. And some of the responses may be inaccurate as people may not feel comfortable saying they’re being harassed – especially who by. Overall, the number of people currently being harassed in the workplace could be much higher than the percentage reported here.

The study only asked about harassment in the past 12 months. It didn’t look at previous harassment situations that have now been resolved. Lifetime harassment exposure in the workplace is unknown and could be higher.

The study isn’t able to delve into how long the harassment has been going on, or the nature of the harassment. These things could give a better indication of how it’s linked with depression symptoms.

The depression diagnoses aren’t clear. The main finding was that people who’d been harassed were a few points higher on the 50-point depression score. It’s difficult to say how much of an effect this difference would have on the person’s health and wellbeing. The researchers looked at the effect on risk of “clinical depression”, but it’s not clear what they meant by this.

We can’t read too much into the risk relationships identified because of several factors: the potentially non-representative sample, the small proportion of employees who reported harassment, and the uncertain diagnoses of depression symptoms.

The study surveyed people from Denmark. This means the findings may not easily be applied to the UK or other countries.

Nevertheless, these limitations don’t undermine the importance of these findings.

Anyone experiencing workplace harassment in any form, whether from clients or customers or colleagues, should feel able to report it.

It’s also important to seek help from a health professional if you’re experiencing symptoms of depression.

Read more about how to look after your mental health.