Validation of antihypertensive drug requirement to measure the severity of hypertension and the efficacy of lifestyle intervention

Abstract

Background/objective: The ongoing pandemic of non-communicable diseases, with systemic arterial hypertension at the forefront, mandates urgent attention to the aetiopathogenic mechanism rather than continuing to rely on suppressive drug therapies. Lifestyle interventions (such as diet, sleep and exercise) may have substantial impact on blood pressure control in hypertension. However this may not be evident in clinical trials of lifestyle intervention if the blood pressure was previously controlled by drugs. We therefore sought to develop an alternative method of measuring the impact of lifestyle intervention, rather than rely on blood pressure measurement alone.

Methods: The open trial of a personalized food avoidance dietary approach to stop hypertension was approved by the UNTH ethics committee. The Antihypertensive Drug Treatment Requirement (ADTR) score was calculated as the total number of defined unitary dosages of antihypertensive drugs times adherence +/- 0.1 accordingly for each mm Hg that average systolic pressure either exceeds 120 mm Hg (AOBP or home BP, whichever higher) or goes below 100 mm Hg Hg (AOBP or home BP, whichever lower). The dietary compliance score was based on the frequency of major/ minor dietary indiscretion (as per the PFADASH guidelines) i.e. less than (= GOOD) or more than (= POOR) once a month/ once a fortnight, respectively. Normality of data distribution was assessed by computing Shapiro-Wilk statistics. Cronbach's alpha reliability coefficient was used to assess internal consistency of ADTR measurements.

Results: Bi-quarterly Shapiro – Wilk statistics for AdhRx scores and ADTR scores showed more than 80% likelihood of being normally distributed at 5% significance level (i.e. 13 out of 16 data sets tested). Cronbach's alpha reliability coefficient was 0.980. This confirmed consistency of the ADTR measurement scale. For three study participants who improved to Good compliance (after dietary counseling) and four participants who failed to improve, Good compliance was associated with lower ADTR scores, but the differences between Good (mean ADTR of 1.07+0.82) and Poor (3.81+3.15) were not statistically significant (p = 0.210). For the three study participants who transited from Poor to Good compliance (in response to counseling), there was a high degree of negative correlation (i.e. decline of drug requirement) which was statistically significant in two of them (p<0.05). However, in the study participants who failed to improve their dietary compliance, there was a relative lack of correlation (with higher p values). The overall pattern is consistent with a negative association between dietary compliance and ADTR score.

Conclusion: We conclude that ADTR scores are useful and valid tools to assess the impact of dietary interventions which address the aetiopathogenic mechanism in essential hypertension. This enables differentiation between blood pressure lowering by drugs and that due to dietary intervention.