Blog entry by Meguid El Nahas
I listened with considerable interest to a BBC radio debate today relating to a published report claiming that 1.8million UK residents are "diagnosed" as suffering from CKD. http://www.bbc.co.uk/iplayer/episode/b01lt2vn/Inside_Health_Overdiagnosis/
On the program, Dr Donal O'Donaghue (Salford, UK) was defending such a growing vue calling for more detection and prevention as well as resources to manage this growing healthcare challenge. In effect, he was championing the prevaling, fashionable, view of rising CKD prevalence, the value of early detection and prevention and so many more often repeated but unsubstantiated and unproven assertions.
Dr Chritopher Winearls (Oxford, UK) was challenging this dogmatic vue, pointing out the inaccuracies of such prevalence statements, issues with detection and prevention programs as well as the grave concern over medicalisation of age-related decline in kidney function.
As often is the case, when the advocate of rising CKD are in trouble with their argument, they fall back on the "But CKD is a major CVD risk factor, so we need to detect it and prevent it...." argumement. One by the way totally refuted by most cardiologists and many nephrologists such as myself for the following reasons:
1. CKD is a MANIFESTATION of underlying CVD not its primary CAUSE, as I stated on many occassions on OLA; I even called the condition Cardio-Kidney-damage (C-K-D) in a 2010 Publication in KI.
2. In support of such argument is that subclinical CVD often precedes incident CKD in older individuals and accelerates its decline.
Here I refer to a number of publications showing that baseline atherosclerosis deteceted by raised carotid intima-media thickness predicts incident CKD (Choncol et al. http://www.ncbi.nlm.nih.gov/pubmed/18388124) and that those with subclinical cerebrovascular disease also have accelerated CKD decline within the community. http://www.ncbi.nlm.nih.gov/pubmed/20537454
This month in cJASN an article by Park et al. report on an observation from the Multi-Ethnic Study of Atherosclerosis (MESA) were they followed up 3,866 individuals (mean age 60) in the USA for approximately 5 years. They reported that those who go on to develop CKD have underlying CVD defined as subclinical cardiac hypertrophy detected by MRI. The presence of ventricular concentricity/hypertrophy increased risk of CKD develkopment (eGFR<60) but also that of increased risk of faster eGFR decline. This was independent of confounders such as hypertension and diabetes.
This supports once more the notion that older individuals with CKD have underlying CVD rather than the other way round. Consequently, it is not surprising that patients with CKD, a marker of underlying diffuse vascular pathology, have a worse CV outcome.
3. And perhaps more importantly, it is most likely that the underlying subclinical CVD that precede CKD may be the reflection of subclinical or underdiagnosed hypertension. In this week's Lancet a series of article stress the fact that systemic hypertension is both underdiagnosed and undertreated in developed as well as developing countries. The fact that casual/office blood pressure measurement is most unreliable and does not reflect 24h ambulatory blood pressure measurements or nocturnal hypertension known to be more closely associated with CVD.
It is likely that it is hypertension and the associated CVD that lead to CKD not the other way round.
30-40% of the population sufferes from hypertension.
Prevention and early Detection of Hypertension: YES, this should be the nephrologists' message!
Ultimately, CKD would, undoubtedly through hypertension and other uremia related factors, accelerate the progression of CVD; a vicious cycle described by Sir Richard Bright almost two centuries ago...!!!!