Incidence and risk factors for type 2 diabetes mellitus in transitional Thailand: results from the Thai cohort study

Background: Type 2 diabetes mellitus (T2DM) is increasingly prevalent in countries undergoing rapid development, including Thailand. We assessed T2DM incidence over an 8-year period in a nationwide cohort of Thai adults. Methods: Thai Cohort Study participants were surveyed in 2005, 2009 and 2013. The analysed cohort members were aged (15–88), did not have diabetes in 2005 and were followed up by questionnaire in 2013 (n=39 507). T2DM was ascertained using self-report, which has been validated using physician interviews. We calculated the 8-year cumulative incidence of T2DM. Multivariable logistic regression assessed associations between potential risk factors and T2DM incidence. Results: 8-year cumulative incidence of T2DM (2005 to 2013) was 177 per 10 000 (95% CI 164 to 190). Crude and age-standardised cumulative incidences of T2DM by sex were 249 per 10 000 (95% CI 226 to 272) and 222 per 10 000 (95% CI 219 to 225) for men; and 119 per 10 000 (95% CI 105 to 133) and 96 per 10 000 (95% CI 94 to 98) for women, respectively. T2DM increased significantly for both sexes with increasing age and body mass index (BMI) ( p trend <0.001 for both). Residence in an urban area as a child associated with T2DM among men and women (OR=1.4, 95% CI 1.1 to 1.7 and OR=1.4, 95% CI 1.01 to 1.79); this was no longer statistically significant after adjusting for BMI. Among men, smoking (OR=1.7, 95% CI 1.3 to 2.2) and alcohol intake (OR=1.8, 95% CI 1.1 to 3.0) were associated with T2DM. Conclusions: This study found that the sociodemographic and lifestyle changes that have accompanied Thailand’s economic development are associated with T2DM risk in a large cohort of Thai adults. Our findings highlight the need to address these transitions to prevent a further increase in the national incidence of T2DM, particularly among Thai men

Methods used for successful follow-up in a large scale national cohort study in Thailand

Background: Ensuring successful follow-up is essential when conducting a prospective cohort study. Most existing literature reviewing methods to ensure a high response rate is based on experience in developed nations. Findings: We report our 4-year follow-up success for a national cohort study examining the health transition underway in Thailand. We began the cohort study in 2005 with a baseline postal questionnaire sent to all 200,000 Thais enrolled as distance learning students at Sukhothai Thammathirat Open University and residing all over Thailand; 87,134 or 44% of the students responded. Subsequently we used University and national media to inform cohort members of study progress. Also, we prepared a health book with study results and health advice which was distributed to all cohort members. After 4 years we repeated the survey and achieved a 71% response rate. In this paper we report the methods used to achieve this response The initial follow-up mail-out generated a response rate of about 48% reflecting the extensive preparatory work between baseline and follow-up. After 4 rounds of telephone contact (more than 100,000 phone calls) and 4 related mail-out rounds progressively over 16 months an overall response rate was achieved of just over 71% (n = 60,774). The total cost was US$4.06/respondent - 19% for printing, 21% for postage, 14% for tape measures (included in mail-out), 18% for data processing 22% for prizes and 6% for telephone. Conclusions: Many of the methods reported as effective for mail questionnaire and cohort response rates held true for Thailand. These included being associated with a university, incentivating cooperation, follow-up contact, providing a second copy of questionnaire where necessary, and assurance of confidentiality. Telephone contact with the cohort and the small prizes given to responders were particularly important in the Thai context as was Thai leadership of the research team

Incidence and risk factors for type 2 diabetes mellitus in transitional Thailand: results from the Thai cohort study

Background: Type 2 diabetes mellitus (T2DM) is increasingly prevalent in countries undergoing rapid development, including Thailand. We assessed T2DM incidence over an 8-year period in a nationwide cohort of Thai adults. Methods: Thai Cohort Study participants were surveyed in 2005, 2009 and 2013. The analysed cohort members were aged (15-88), did not have diabetes in 2005 and were followed up by questionnaire in 2013 (n=39 507). T2DM was ascertained using self-report, which has been validated using physician interviews. We calculated the 8-year cumulative incidence of T2DM. Multivariable logistic regression assessed associations between potential risk factors and T2DM incidence. Results: 8-year cumulative incidence of T2DM (2005 to 2013) was 177 per 10 000 (95% CI 164 to 190). Crude and age-standardised cumulative incidences of T2DM by sex were 249 per 10 000 (95% CI 226 to 272) and 222 per 10 000 (95% CI 219 to 225) for men; and 119 per 10 000 (95% CI 105 to 133) and 96 per 10 000 (95% CI 94 to 98) for women, respectively. T2DM increased significantly for both sexes with increasing age and body mass index (BMI) (p tren