Controversies over hypertension guidelinesBMJ 2012; 344 doi: https://doi.org/10.1136/bmj.e653 (Published 25 January 2012) Cite this as: BMJ 2012;344:e653
All rapid responses
What is this evidence base that we talk about; that too in a “risk factor arena” of elevated blood pressure, which has been elevated to a full blown “silent killer” disease. Let us analyse the so called evidence base very calmly from the beginning.
The largest and possibly the longest follow up study, MRFIT, has just given us the following data, if one were to go by the data alone. The conclusions of MRFIT analysis by Dr. Roger W. Sherwin is quite shocking: “The original goal of the MRFIT was to determine whether reduction of the risk factors smoking, cholesterol and elevated blood pressure in high-risk but otherwise healthy men would reduce CHD mortality, non-fatal MI or CHD, cardiovascular mortality and mortality from all causes. (1) Their paper answers these questions thus:
"In conclusion we have shown that it is possible to apply an intensive long-term intervention program against three coronary risk factors with considerable success in terms of risk factor changes. The overall results do not show a beneficial effect on CHD or total mortality.”
In other words, they found that changing the "risk factors" does not apparently change the risks. This necessarily means that the "risk factors" are not as important as they are thought to be. Indeed, it should be concluded that the "risk factors" were no such thing, at least as far as MRFIT trial is concerned.
· Diastolic pressure has no clinical significance; it is only the systolic pressure that matters, if anything! Most of our RCTs in this area are based on the diastolic reading!
· The linear science of MRFIT study shows that any level of systolic pressure is better than its higher level! No cut off point at all!
· Therefore, if 110 systolic reading is good 100 would be better and so on.
· What does our evidence base tell us? Strictly speaking scientifically, systolic pressure of zero is better than 10 mmHg! Will any one survive with zero pressure?
· All RCTs in hypertension arena are based on surrogate end point of BP level coming down. What happens to the patient? No study has reported the real end point of death for the guidance of the NICE guidelines creators. However, by default, there is one study which was stopped prematurely because of the real end point data. The HOT study was stopped in eighteen months (it was to go on for five years) but published with a comment thus; “better drugs in larger does bring the pressure down very effectively and so the study need not continue.” (2) The truth is that nearly 27% more patients died in the treated group within 18 months compared to the control group which was deemed dangerous to continue the study protocol. So the only one end point (death) study did show that effectively and quickly lowering the BP with powerful drugs is a sure exit Visa from this world!
· RCTs themselves are under a dark cloud these days. No two humans are alike. Where is the scientific basis for matching based on a few phenotypical data? The NICE Director, Sir Michael Rawlins, had opined in his Harveian Oration in 2008: “that RCTs have been put on an undeservedly high pedestal”! (3)
· Let us look at the physics of Blood Pressure in the first place. Everything flows by whirling in nature. How do we know that blood flow inside the vessel is laminar. If it is laminar, it can not exert later pressure on the vessel wall as Co sine 90 is zero. Our definition of blood pressure is latteral pressure exerted by the flowing blood on the vessel wall. Studies have now shown that blood probably flows by whirling only even inside the large blood vessels. Capillary flow is by capillary chaos! Moreover, when a blood vessel gets blocked with atherosclerotic plaques, what happens to blood pressure (if flow is laminar) depends on the Bournelli Effect, and not what we project in our textbooks! (4)
· If we put all the 17 studies of BP in the literature together, the inclusion criteria will fit only about 39% of the hypertensive population. Where is the evidence base for the rest of the 61% patients? This is my observation.
Uffe Ravnskov’s analysis of survival benefit, RRT, and absolute risk reduction (ARR) shows our evidence base in very poor light! (5)
Relative Risk Reduction% -20 -21
Absolute risk reduction % -0.8 -3.3
Survival chance without drugs % 96 88.5
Survival chance with drugs % 96.8 91.8
If we look carefully modern medicine deep down is very, very shallow. (6, 7, 8, 9, 10, 11, 12)
1) Zukel WJ, Paul O, Schnaper HW. The multiple risk factor intervention trial (MRFIT). I. Historical perspective. Prev Med. 1981 Jul;10(4):387-401.
2) Hot Study Group. www.thelancet.com/journals/lancet/.../PIIS0140-6736(98)04311-6
3) Rawlins M. The Harveian Oration of 2008. De Testimonio. On the evidence for decisions about the use of therapeutic interventions. Royal College of Physicians, 2008.
4) Hegde BM. Where is the reality? www.kma.org.kw/kmj/Issues/dec2002/where%20is.pdf
5) Ravnskov U. Chance of surviving with and without treatment. 18 June 2002 ... www.bmj.com/content/324/7350/1353.2?tab=responses
6) Marcia Angell. Pt. Preferences in RCTs. NEJM 1984; 310:1385-87.
7) Clarke CJ. Rapid determination of number of patients required for RCT. Lancet 1966; 11: 1357.
8) Cromie BW. Feet of clay of RCTs. 1963; 11; 994-997.
9) Freidman, Howard S. RCTS and common sense. Am. J. Med. 1986; 81: 1047.
10) MRC streptomycin trials BMJ 1948; 11: 769-782.
11) Harris L Coulter. The Controlled Clinical Trials by Centre for Empirical Medicine and Project Cure Washington DC 1991. ISBN 0-916386
12) Sherwin RB. MRFIT study. www.chelationtherapyonline.com/articles/p154.htm
Competing interests: No competing interests