The use of Fourier analysis in the calculation of trough to peak ratio from ambulatory blood pressure measurements

Abstract

The trough:peak (T:P) ratio serves as an index of efficacy of antihypertensive drugs with respect to their dose and dose interval. There is no consensus regarding the method for the calculation of the T:P ratio. We assessed the influences of curve smoothing, the average fall in 24-h mean arterial pressure (MAP) and the length of the peak effect period on the result of T:P ratio calculation. Forty-two patients with essential hypertension (aged 27-81 years; 20 males) had a 24-h ambulatory blood pressure (BP) measurement on two occasions. The first was performed at baseline, the second after 12 weeks of treatment with a ␤-blocker, angiotensin-converting enzyme inhibitor, calcium slowchannel blocker, diuretic or a centrally acting drug, all taken once daily. BP data were analysed both by Fourier analysis (FA) with four harmonics and by time block analysis (TBA). The peak effect was defined as the maximum drop in MAP over a period of 0 to 3 h following drug intake at any time in the 24 h, and the trough effect as the fall in MAP over the last 2 h of the dose interval. FA gave higher T:P ratio values than TBA (0.51 vs 0.43;

Lisinopril versus enalapril: evaluation of trough:peak ratio by ambulatory blood pressure monitoring

“…6 This rather arbitrary limit seems meaningless, however, unless the method by which the T:P ratio of a drug is determined is specified. 15,[17][18][19][20][21][22] In the last years, many excellent reviews addressing the methodology of T:P ratio assessment, especially from 24-h ABPM data, have been published. [15][16][17][18][19]21,22 In these papers, many recommendations have been made for calculation of T:P ratios.…”

“…Furthermore, Fourier analysis with four harmonics was applied to the raw data to obtain smoothed BP profiles. 20 The peak effect was defined as the maximal drop in pressure over any period of 2 h using moving averages. The trough effect was defined as the drop in pressure over the last 2 h before drug administration.…”

“…[14][15][16][17][18][19] Recently, we have found that T:P ratios can be reliably calculated from 24-h ABPM data after Fourier analysis with four harmonics. 20 Furthermore, to prevent erroneous T:P ratio values, peakand trough-effect periods of 2 h each should be used and the peak effect should not be determined within a preset time window. 15,20 In the present study, using a crossover design, the possible differences in magnitude and duration of action of enalapril and lisinopril were further investigated in patients with essential hypertension by choosing the doses on the basis of the office BP response.…”

“…20 Furthermore, to prevent erroneous T:P ratio values, peakand trough-effect periods of 2 h each should be used and the peak effect should not be determined within a preset time window. 15,20 In the present study, using a crossover design, the possible differences in magnitude and duration of action of enalapril and lisinopril were further investigated in patients with essential hypertension by choosing the doses on the basis of the office BP response. The doses of the drugs were titrated until an office BP of less than 140/90 mm Hg was achieved.…”

Comparative study of efficacy and adverse effects profile of azilsartan, olmesartan and candesartan in the control of essential hypertension

“…[10][11][12][13][14][15] Azilsartan, an angiotensin type 1 (AT1) receptor blocker (ARB) was recently approved by regulatory clinical market. The development of AT1 receptor blockers (ARBs) can be traced back to the pioneer work of scientist at Takeda pharmaceutical who described a series of benzylimidazole compounds that inhibited the ability of angiotensin to stimulate the vascular contraction and increase blood pressure (BP).…”