Why we need to be careful with screening eating disorders
Eating disorders are becoming more and more common with the ideals society increasingly places on how men and women’s bodies should look like. While we see women’s curves being appreciated in historical paintings, we also witness an increasing interest in being “skinny” when we move forward to the 1990’s and the “supermodel” trend. When we look at men’s bodies, we see that having big muscles is seen as being “sexy” and therefore also a norm for what their bodies should look like. Nowadays there is ambiguity because one day the norm is being skinny, one day it is being fit and having muscles and one day it is having big curves. Of course this is increasingly contributing to people being dissatisfied with how their bodies look like for both men and women and we see higher prevalence of teenagers suffering from eating disorders.
While some see eating disorders as people being weak in controlling their food intakes, it is important to realize how fatal these disorders can actually be. It is a crucial contributor to suicide rates among teenagers and it can also lead to hundreds of health problems ranging from teeth decay to heart disease. That is why targeting at risk populations for prevention and finding treatment methods is so important.
One of the questionnaires designed to find at risk people for eating disorders is the SCOFF questionnaire. SCOFF is designed as a 5-item screening questionnaire that sometimes includes two further questions in some cases to help decision making that best suits the patient and these two questions have high reliability and validity for Bulimia Nervosa.
The initial validity study done by the creators of the test found the sensitivity value (proportion of true cases screening positive) as 100%, specificity value (proportion of true non-cases screening negative) as 87.5% and positive predictive value (proportion of screen positives found to be true cases) as 90.6%. These values are all very high and promising. However, other studies examining the same test found values that were much different and less promising. One study found sensitivity as 84.6%, specificity as 89.6% and PPV as 24.4% and another found sensitivity as 78%, specificity as 88% and PPV as 47.7%. Another study looking at US populations found the reliability of the test as .44 and sensitivity as 72%, specificity as 73% and PPV as 35%.
These numbers may look boring or arbitrary but differences in these values create a problem with the screening process provided by the test. In my own experience with SCOFF, the test did not screen me as at risk according to the cutoff point of 2 points. This result was a little shocking for me because I was almost sure that I had an eating disorder. A few weeks later I was diagnosed by a psychologist with an eating disorder.
The importance of my experience and the studies investigating these variables for the SCOFF test is that these screening procedures are important in determining who might develop and suffer from these dangerous disorders. For me, the most important job of a screening test is sensitivity because in the case of fatal disorders, false negatives mean more than false positives. People are not going to be diagnosed and stigmatized as a result of a simple screening test and diagnosis can come with further interviews and testing. The crucial thing is to not miss anyone whose lives can be in danger as a result of a potential eating disorder.
STUDENT ID: 260520160
S — Do you make yourself sick because you feel uncomfortably full?
C — Do you worry you have lost control over how much you eat?
O — Have you recently lost more then one stone (6.35 kg) in a three-month period?
F — Do you believe yourself to be fat even when others say you are too thin?
F — Would you say food dominates your life?