Measured Variables
Creators: name: Khanolkar, Amal R.
Publisher: name: OSF Registries
Year: 2019

description: We will use the parent reported 5-item Rutter internalising scale and the self reported symptoms on the 9-item Malaise inventory as the primary measures of internalising symptoms at age 16. Parents reported on the child’s mental health using the Rutter A scale, a set of questions which combine to give an index of mental health difficulties in the child (Rutter, 1967b, Rutter et al, 1970). Internalising subscale consists of five items assessing symptoms and responses are provided on a three category scale from 0 to 2, where 0=‘Does not apply’, 1=‘Applies somewhat’ and 2=‘Certainly applies’. Adolescents self-reported their symptoms using the Malaise Inventory. Items on this questionnaire asked cohort members whether they often ‘feel miserable and depressed’, ‘get worried about things’ and ‘get easily upset or irritated’ with a ‘yes/no’ response. As a sensitivity analysis, we will also compare a ‘harmonised’ 5-item measure that selects 5 common items from both measures that assess the same symptoms. This additional sensitivity analysis helps understand whether the parent-child associations vary based on the item content of the measure, both concurrently at 16 and in terms of predicting outcomes at age 42. 
To investigate high levels of symptoms, we will use the score closest to the 85th percentile for parent and self reported symptoms (the Rutter scale does not have an established cut-off score and researchers have used the 85th percentile in previous publications). Based on the cut-points for the two measures, binary variables can be created for parent and child report. These can be used to identify four groups at age 16: 1) above cut-off based on both reporters, 2) below cut-off based on both reporters, 3) above cut-off based on self report only, 4) above cut-off based on parent report only. 

Outcomes at age 42: We will investigate associations between mental health at age 16 and a range of outcomes at age 42, including health and wellbeing (BMI, obesity, psychological distress, mental wellbeing and life satisfaction), lifestyle factors (smoking and alcohol consumption) and socioeconomic outcomes (highest educational level achieved, home ownership, employment status, income levels, ,occupational class partnership status, having children and voting behaviour). 

Health and wellbeing: At age 42 psychological distress was measured using the 9 item Malaise Inventory (Rodgers, Pickles, Power, Collishaw, &amp; Maughan, 1999), a total score and a binary indication of above or below cutoff (score above 3) are examined. Mental wellbeing was measured using the Warwick-Edinburgh Mental Wellbeing Scale. This scale comprises of 14 separate items measured on a 5 point Likert scale which are summed to give a total score of wellbeing ranging from 14 to 70 (a higher score reflects higher levels of wellbeing). Life satisfaction was measured through asking cohort members to rate ‘How had life turned out so far’: on a scale of 0 to 10. Participants were asked to rate their general health using 5 categories (1= Excellent; 2 = Very good; 3 = Good; 4 = Fair; 5 = Poor) and good health was coded 1 and indicated whether they have a longstanding or chronic illness (yes/no). Height and weight (self-reported) will be used to calculate BMI (using the standard formula of weight (kg)/height (m)2. Further, BMI will be divided into three categories according to the World Health Organization criteria with ‘overweight’ defined as BMI between 25–29.99 kg/m2 and ‘obesity’ as BMI ≥30 kg/m2. Participants will be classified into current smokers or not. Alcohol consumption was investigated based on frequency (2 or more time a week coded 1). 

Social and economic outcomes: Social and economic outcomes at age 42 are self-reported and include partnership status at 42 (yes/no) and whether have a child (yes/no). Highest academic qualification was recorded using the highest NVQ level and a binary variable was derived indicating whether participants had a higher degree/diploma vs no degree. Employment status at age 42 is a binary variable (currently employed vs unemployed including those with sickness or disability). Home ownership (own/rent and other) and income (log transformed) are also included as measures of socio-economic position. Voting behaviour (voted/did not vote) will be based on participation in the previous national elections in 2010. 

Covariates: Cohort member’s sex, childhood socioeconomic position (parent occupational class and education).