Misclassification

6.6.1.1 Misclassification of depression

Some adolescents may have been classified as not having depression or depressive

symptoms, even though they have a depression. Misclassification of self-reported symptoms can have occurred because adolescents can lack in their ability to recognize symptoms which possibly can differ between social groups, and between boys and girls [48]. It is possible that self-reporting of depression are affected by what Johansson [301] mention as “the modesty of the poor as well as the dissatisfaction of the rich‟. It means that those with higher SES

possibly expect better health and thereby report symptoms at a lower threshold than those with lower SES. This possible misclassification can attenuate the social differences.

However, differential reporting according to parental SES has previously been found to be a minor concern [302].

Misclassification of diagnosed depression from the care giver can have occurred because of reluctance in diagnosing children [303], as well as the possibility of misdiagnosis, or that some do not seek care [16]. It cannot be ruled out that the same health care provider diagnoses differently depending on the adolescent social characteristics. It has further been found that clinicians can find it difficult to use symptoms based criteria because people can express symptoms differently depending on for example, gender, social position or origin [166]. The incidence presented may therefore underestimate the true levels of depression in the population.

The more important limitation in study II is that social differences in care-seeking can be present, which introduce bias [29]. The direction of the bias is however not clear. Finnish studies [35, 204] suggest that children of parents with higher socioeconomic position may have better access to care. Highly educated adult persons with depression and/or anxiety in Sweden have however been found to be less likely to seek care [15]. Differences in care

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seeking can also apply to gender and ethnic background, where boys in later adolescence and those with parents from ethnic minorities are less likely to seek care [304]. This would result in an underestimation of the risk. On the other hand some care in the private sector was not included in the current analyses, and if those with higher social position to a higher extent seek private care this would lead to an overestimation of the results. Most care in Stockholm is however public [305]. In study III only care-seeking individuals were included.

Study II and III has a design where routine procedures at CAMHS were used. It means that nothing was created for the purpose of these studies specifically. The diagnostic procedures at CAMHS are based on professional assessment and not on structured forms. These procedures are reliable and good, however the precision in the diagnostic procedure can be hard to assess and it is not sure comorbid psychiatric diagnoses and the CGAS-value have been assessed in a structured manner for all cases. CGAS have however been widely used [306] and has a moderate reliability (ICC=0.73) [307]. Some adolescents from CAMHS can further have been classified as having depression but in fact having bipolar disorder. This is due to the diagnostic code system used at CAMHS where a general code, code 19, include all depressive disorders, also bipolar disorder. However, bipolar disorder has a very low prevalence in young samples (around 0.1%) [308].

6.6.1.2 Misclassification of social position

Misclassification of social factors is possible though not likely to be large and also to be non- differential. One issue that can misclassify adolescents to a lower social position than the accurate is however related the procedures for registering housing in the Swedish registers used for study II and III. Only one social context is considered for adolescents with alternate living arrangements as registration in Sweden, is allowed at one address only. Among 6-12 year olds 73% live with both original (biological or adoptive) parents and this has been rather stable the last 10 years [217]. It is however likely that both parents have a similar social position. Furthermore, the second parent was excluded if he or she was not a

biological/adoptive parent, since information for those was differential due to housing conditions, which in turn can be related to social position. This may lead to an

underestimation of the associations.

An additional problem with those with alternate living is that they can have experienced a change in their social context, such as divorce/separation or parental death. Among Swedish 17 year olds approximately 30 percent have experienced divorce/separation and three percent have experienced parental death [217].

The measure of income benefit suffer from the same errors of family composition. Some information can also be lacking due to undeclared income.

The measure of parental country of origin has been discussed to possibly mask the parents’ true ethnic identity. However the groupings of Sweden, Nordic and outside Nordic would not suffer as much from this. The groupings made in the studies of this thesis do nevertheless put

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together large and possibly heterogeneous groups of people. An issue related to classification of occupation is that some report that it can be more difficult to distinguish between more typical female occupations than between more typically male occupations which can partly mask a social gradient among woman [309].