Outcomes

To capture self-rated health, respondents were asked to rate their current health status on a 5-point scale where 1 = excellent, 2 = very good, 3 = good, 4 = fair, and 5 = poor. The order was reversed for ease of interpretation with a value of 1 for poor health and a value of 5 for excellent health. A binary variable representing ‘poor health’ was also created where the responses fair and poor = 1 and excellent, very good, and good = 0. Psychological distress was measured using the General Health Questionnaire composed of 12 items [81, 82]. This tool has been widely used in mental health research and previous studies have demonstrated its validity and usefulness in several contexts, including India [83–85]. The items ask whether the respondent has recently experienced a particular stressful symptom or behavior. Each item was rated on a 4-point scale (0 = “less than usual”, 1 = “no more than usual”, 2 = “rather more than usual”, or 3 = “much more than usual”). Items were rescored using 0-0-1-1 responses as other studies have previously done. The items were then summed together with a total possible score ranging from 0 to 12, which was treated as continuous variable. A higher score indicated a greater degree of psychological distress. Probable ‘common mental disorder’ was derived from the psychological distress score by creating a dichotomous variable using a cutoff of 5 or less vs. 6 or higher with the latter indicating a probable common mental disorder’ [86]. Immediate recall of words was used to measure cognitive ability [87]. A list of 10 commonly used words was read out to the respondents, who were then asked to recall the words within two minutes. The number of words recalled (0 to 10) was recorded. Therefore, a higher score represented better cognitive ability.

Four chronic morbidity outcomes were measured by asking, separately, whether the respondents had ever been told by a doctor or a nurse that he or she had high blood pressure (hypertension), diabetes, arthritis, or asthma (yes/no responses). A binary variable indicating whether a respondent had been told that he or she had one or more of those four diseases was created.