We adjusted for ethnicity which may have cultural influence on the perception of diseases. We also adjusted for other comorbid conditions that might influence HRQoL. There were several limitations worth mentioning. The cross-sectional nature of this study prevents examination of any causal relationship between disease awareness and medication in these conditions and HRQoL. Known disease status was obtained through self-report, which is subject to reporting and recall bias, and is therefore a limitation. Since this was a community survey, we were unable to include any examination of medical records to assess accuracy of such self-report, and this is a limitation of the study. Single time-point measurements were used to classify participants’ disease status, unlike in the clinical setting, and therefore there is potential for erroneous classification of participants. However, other nationally representative surveys have also shown significant proportions of respondents with previously undiagnosed disease, and therefore it appears that under-diagnosis of these conditions is a true rather than artefactual finding. The number of individuals with known diabetes and not taking medication was small. However, our findings in WZ8040 EGFR/HER2 inhibitor relation to HRQoL for all the three conditions are in agreement with a recent report in Thai population. Therefore it is unlikely that the smaller numbers in this particular category affect the associations reported in this paper. It needs to be pointed out that though the differences in HRQoL scores after adjustment appear small, unadjusted difference in PCS scores ranged from 3–5 points, which is in the range deemed clinically significant. Perceptions of illness and health are influenced by cultural contexts; therefore findings may not be fully generalizable to other populations. However, these findings still have direct relevance to populations with sizeable representation from Chinese, Indian or Malay ethnicities. In summary, we have found that persons with diagnosed diabetes, hypertension or dyslipidemia have lower HRQoL, and this association is greatly influenced by presence of comorbid conditions. Importantly, treatment with medication, especially in diabetes and hypertension, was not associated with any adverse effect on HRQoL. This reinforces the importance of initiating treatment at the time of diagnosis, early in the natural history of these conditions, to prevent the development of comorbities. Equally importantly, individuals with undiagnosed disease have similar or better HRQoL compared to the non-diseased population. Thus a more robust implementation of the health screening strategy for cardiovascular disease and risk factors is needed to detect and to treat these individuals early to prevent complications. At the same time, we need to consider strategies to limit the impact of disease awareness on HRQoL. Psychiatric disorders of thought are usually characterized and diagnosed on the basis of clinical assessment of an individual’s verbal and physical behavior. This is the conventional way to assess a thought disorder.