Response to Knowing Hypertension Awareness and Psychological Distress in Primary Prevention
We are pleased by the interest in our article on hypertension awareness1 and thank Shiue2 for highlighting several important issues that may have relevance in terms of primary prevention. The following analyses hopefully provide some additional insight.
The first point requested how education level and/or social class might influence the degree of psychological distress and hypertension awareness. In the present study, socioeconomic status was assessed using the Registrar General Classification (professional/intermediate, skilled nonmanual, skilled manual, or part-skilled/unskilled), a standard approach for studies conducted in the United Kingdom. As has been demonstrated elsewhere, in comparison with the highest social status participants (professional/intermediate), those from the lowest social status (part-skilled/unskilled) were more likely to demonstrate psychological distress (age and sex-adjusted odds ratio [OR]: 1.56 [95% CI: 1.44 to 1.69]). However, the proportion of lower social status participants did not differ in study members who were “aware” (23.8%) and “unaware” (21.5%) of being hypertensive. As such, additional adjustment for social status did not alter the association between hypertension awareness and psychological distress (fully adjusted OR: 1.56 [95% CI: 1.40 to 1.73]). We would, therefore, conclude from these additional analyses that social status does not influence the observed associations between hypertension awareness and psychological distress.
A second issue raised is whether a higher risk of psychological distress is observed among detected but untreated hypertensive patients. We observed associations between antihypertensive drug use and psychological distress, which was particularly robust among users of diuretics (multivariate adjusted OR: 1.21 [95% CI: 1.07 to 1.36]) and calcium blockers (multivariate adjusted OR: 1.25 [95% CI: 1.08 to 1.44]). However, when we removed participants taking antihypertensive drugs (n=5069), there remained an elevated risk of psychological distress in aware hypertensive participants (age- and sex-adjusted OR: 1.64 [95% CI: 1.49 to 1.81]). Thus, it appears that the risk of psychological distress is also apparent among detected but untreated hypertensive patients. In a related issue, Shiue2 was interested in examining whether patients who did not comply with blood pressure–lowering medication experienced an elevated risk of psychological distress. Unfortunately we do not have information on medication adherence in the present study. However, we agree that psychological factors may be important determinants of adherence to antihypertensive medication, and in a recent study, a high sense of coherence was associated with antihypertensive medication-adherence behavior.3
Lastly, Shiue2 has suggested that presenting the mean General Health Questionnaire score might have more relevance as oppose to using the commonly used ≥4 cutoff score to identify psychological distress. In general, we certainly agree that using continuous data is preferable to categorization as power and information are retained. However, in the present study, mean General Health Questionnaire scores displayed a highly skewed distribution, and, therefore, performing parametric tests on the data would be inappropriate and could lead to erroneous results. The used ≥4 cutoff score to identify psychological distress has been validated previously by clinical interview.4
Sources of Funding
The Scottish Health Survey is funded by the Scottish Executive. The Health Survey for England is part of a programme of surveys commissioned by The UK National Health Service Information Centre for health and social care, and carried out since 1994 by the Joint Health Surveys Unit of the National Centre for Social Research (NatCen) and the Department of Epidemiology and Public Health at the University College London Medical School. M.H. is supported by the British Heart Foundation (RG 05/006); E.S. is funded by the National Institute for Health Research, UK; G.D.B. is a Wellcome Trust Career Development Fellow (WBS U.1300.00.006.00012.01); M.K. is supported by the National Heart, Lung, and Blood Institute (R01HL036310) and the National Institute on Aging (R01AG034454), NIH, US, the BUPA Foundation, UK, and the Academy of Finland, Finland. The funders played no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript. The views expressed in this article are those of the authors and not necessarily of the funding bodies.