Friday January 16 2009
Postnatal depression affects about one in 10 mothers in the UK
The Guardian reports today that, “Postnatal depression, which affects 13% of mothers and can lead to suicide, could be treated without drugs, and even prevented." The newspaper said new research suggests that new mothers could benefit from the support of health visitors and other women who have had postnatal depression.
The newspaper report is based on the findings of two separate studies published in the British Medical Journal. The first study (in England) found that postnatal depression is reduced in women if health visitors are trained to spot symptoms of depression six to eight weeks after birth, and offer psychological support. The second (Canadian) study found that women who received advice by phone from a woman who had suffered herself were around half as likely to develop postnatal depression 12 weeks after birth.
Both these studies are reliable, and provide good evidence of the benefits of counselling and its practical application for new mothers. This is important research as around one in 10 mothers in the UK are thought to experience postnatal depression. A structured programme for delivering this type of intervention now seems likely.
Where did the story come from?
Dr C Jane Morrell from Sheffield University and colleagues from the UK and US carried out the first study. This research was funded by the NHS research and development programme. The second study was carried out by Professor Cindy-Lee Dennis from the University of Toronto and colleagues from Canada. Funding was provided by the Canadian Institutes of Health.
Professor Dennis is also the author of a systematic review on the topic. She wrote an accompanying editorial in the peer-reviewed British Medical Journal (BMJ), in which both studies were published.
What kind of scientific study was this?
The first study is a cluster randomised trial, which ran between 2003 and 2006. It aimed to evaluate how the effects of training health visitors to identify postnatal depressive symptoms and provide psychological interventions compared against standard care. The health visitors assessed women’s depressive symptoms six to eight weeks after they gave birth, using a recognised scoring system, the Edinburgh Postnatal Depression Scale (EPDS), along with a clinical assessment.
Depression was identified in around 4,000 women in England, who were treated in one of three possible ways. A third received a “psychologically informed” session based on cognitive behavioural principles (a therapy aimed at changing behavioural responses). Another third received a session based on person-centred principles (a therapy that encourages a woman to discuss their feelings). The final third were offered the usual GP referral. The psychological sessions took place for one hour a week for eight weeks, and were provided by the health visitor.
The type of treatment the women received was decided by a process called cluster randomisation. This involved 101 urban and rural general practices (clusters) in 29 primary care trusts in the former Trent Regional Health Authority. Each surgery was randomly chosen to adopt one of the three treatments so that all the women from each practice were treated in the same way. Women were followed for 18 months, with progress measurements after six months and 12 months.
The second study is also a randomised controlled trial, which enrolled more than 21,000 women from seven different health regions across Canada. This trial involved about 700 women two weeks after they gave birth, who had been identified by the EPDS as being at high risk of developing postnatal depression. These women were randomly allocated to one of two interventions. Half received telephone support from specially trained volunteer mothers who had experienced postnatal depression themselves. The other half were given standard community postnatal care, in which they could seek help from various health professionals if they felt it necessary.
The telephone-based mother-to-mother support began within 48-72 hours of randomisation. The women offering advice had previously experienced and recovered from self-reported postnatal depression. These women were recruited from the community and had attended a four-hour training session.
What were the results of the study?
In the English trial, the women who received either of the two types of psychological therapy were found to have significantly lower levels of depression compared with the others who received standard GP care. A third of women who had received therapy still had symptoms of depression six months after their baby's birth, compared with just under half of those in the control group. These differences in outcomes remained significant when women were assessed again at 12 months.
In the Canadian trial, those who received peer support in the form of regular telephone conversations were half as likely to become depressed by 12 weeks after birth. More than 80% of those who received telephone support said they were satisfied with the experience and would recommend it to a friend.
What interpretations did the researchers draw from these results?
The researchers in the English trial say that “training health visitors to assess women, identify symptoms of postnatal depression, and deliver psychologically informed sessions was clinically effective at six and 12 months postnatally compared with usual care”.
The Canadian researchers say that “telephone-based peer support can be effective in preventing postnatal depression among women at high risk”.
What does the NHS Knowledge Service make of this study?
These randomised controlled trials both provide high-quality evidence that practical approaches to treating or preventing postnatal depression are effective.
There were high rates of participation in the large English trial, and although the authors acknowledge potential limitations, these would not be enough to alter the main conclusion. The limitations the authors discuss include:
- Each treatment had varying numbers of women dropping out before the end of the study, and the two treatment groups had more women leave within the first six months than the group that received standard care.
- This was a pragmatic trial, meaning that the researchers included a wide variety of participants in an effort to be more representative of the population that would receive the intervention in real life. This is in contrast to non-pragmatic trials, which often include a very narrow spectrum of people (e.g. those with a specific level of depression and with few other medical problems). One of the consequences of this design is that it is hard to explain why there was a reduction in depressive symptoms in all the women who received the interventions, irrespective of depression score. However, the authors say that a pragmatic trial does not seek to explain this effect.
- Because the interventions also included social interactions, such as the contact made by health visitors in the antenatal period, it is possible that the psychological treatment alone may not be responsible for the effects seen. However, in this type of trial design, the exact nature of the intervention is difficult to standardise and report on in detail, as all the health visitors might have delivered the intervention in slightly different ways, or developed different bonds with the mothers. The researchers recommend a further trial to determine exactly what part(s) of the intervention were responsible for the effect.
In the Canadian trial the researchers say:
- Their results are limited in that the diagnosis of postnatal depression might be questionable. They used a structured clinical interview that was developed for use by a mental health specialist in person. However, in this trial it was necessary to conduct the interview over the telephone and to have generalist nurses administer it. A shortened version of the depression module was also used, but this use has not been formally validated.
- Their sample was significantly more ethnically diverse than the sample in the one previous postnatal depression study, which administered the same interview by telephone. It is not clear if the questionnaire was appropriate or understood by women from a range of ethnicities.
Writing in an editorial on the two papers published in the same issue of the BMJ, Professor Cindy-Lee Dennis, who led the second study, said that both studies provide “more evidence that postnatal depression could be effectively treated, and possibly even prevented”. A structured programme for delivering this type of intervention now seems likely. Further study needs to assess the cost of the intervention, and assess which precise aspect of interacting with a health visitor helped the new mothers.
Sir Muir Gray adds...
Very important finding on a very important topic.