Ok, on the issue of the comparison with the hypertension group:
First, Figure 1 has nothing to do with the hypertension group. The issues of comparing the ME/CFS group with a highly selected cohort with no diseases at all remain regardless of the comparison with the hypertension group.
The study population included a heterogenous ME/CFS cohort, seven homogenous comorbid cohorts (hypertension, depression, asthma, IBS, hay fever, hypothyroidism and migraine) and a non-diseased or ‘healthy’ cohort (C2) (Supplementary Table
1). A heterogenous cohort was defined as the presentation of multiple, and different medical conditions and homogenous refers to the existence of one single condition.
Second, is the issue that I covered upthread. The paper tells us that the ME/CFS group is a heterogeneous cohort - they are allowed to have multiple health conditions including Type 2 diabetes and obesity (these being among the health conditions recorded in the UK biobank). The paper tells us that the disease comparisons involve homogeneous cohorts, that is, the people in these cohorts do not have other diseases, only the one that labels their group.
So, people in the Hypertension group only have hypertension. They don't have Type 2 diabetes, they don't have obesity. There are 13,559 of them.
You can see how selective the group is by comparing how many people in the UK Biobank have a self-reported diagnosis of hypertension - 27%, 135,787 people. (from Cohort profile of the UK Biobank: diagnosis and characteristics of cerebrovascular disease). Treated hypertension accounts for 99,468 participants in the UK Biobank (from Prevalence and determinants of hypertension control among almost 100,000 treated adults in the UK). Another study (Prevalence and determinants of hypertension control among almost 100,000 treated adults in the UK) analysed the UK Biobank data and, after excluding people with serious comorbidities such as major cancer and pregnancy, found 256,203 people were hypertensive based on the blood pressure reading at baseline, 55.8%.
The people in the Hypertension comparator used in this paper are therefore a highly selected group of people, essentially they are super healthy hypertensives, having only hypertension and no other diagnosed health condition. The same problem applies to all of the homogeneous disease comparators.
It's not a reasonable comparison, to compare the lipid profiles of the ME/CFS group, which does include people with metabolic disease and obesity, with a group that does not include those people, and make claims that you have found something that useful characterises ME/CFS. Maybe you have found something useful, probably you haven't, we can't know.
Third, even setting the considerable issue of the high selectivity for lipid health that has gone on in the comparator groups, we aren't seeing super big differences between the ME/CFS group and the Otherwise Healthy Hypertension group.
The Odds ratios shown in Supplementary Material 4 gives the following (these are odds compared to the C2 No diseases group)
Total free cholesterol: ME/CFS 0.98; Otherwise Healthy Hypertensive 0.94
VLDL FC: ME/CFS 1.27; Otherwise Healthy Hypertensive 1.10
LDL FC: ME/CFS 0.94; Otherwise Healthy Hypertensive 0.92
HDL FC: ME/CFS 0.69; Otherwise Health Hypertensive 0.83
Total cholesterol: 0.92; 0.91
Non-HDL-C: 1.06; 0.98
remnant C: 1.09; 0.98
VLDC-C: 1.23; 1.07
Clinical LDL: 1.01; 0.96
LDL-C:1.03; 0.97
HDL-C: 0.65; 0.83
I think those odds ratios indicate the Otherwise Healthy Hypertensives are nowhere near indicative of people with hypertension in the age range of the UK Biobank. All the searches I have done for rates of dyslipidemia in people with high blood pressure suggests that rates are substantially higher than in the general population. Weirdly, a lot of the papers seem to be from low income countries.
I wish that actual levels of the blood lipids had been reported as that would have made it easier to compare across studies.
Anyway, there is the same problem with the comparator group with the comparison against the super healthy controls. In both cases, you are taking the ME/CFS population which includes people with a range of BMIs and comorbidities and comparing them to groups of people where no one is obese or has other health conditions that might affect blood lipids.
I'm with you @MelbME on this.
I maybe the only one here on s4me who likes real healthy controls.
I understand when doing CPET research you do not invite the Tour the France peloton as healthy controls.
But in this kind of research you want to find the differences in ME/CFS and healthy controls, nor almost sick and ME/CFS.
Are you trying to be holier than the Pope here @Hutan ?
Not at all
@Turtle. I'm trying to understand what happened with this research, in order to try to improve what we know about ME/CFS and make sure research funds and effort aren't wasted. There is a real issue here to be addressed. I'm a bit surprised people aren't seeing the problem.
Turtle, you are exactly right about not comparing a group of people with ME/CFS with the Tour de France peloton when drawing conclusions form a CPET test. It's the same principle with this research, it's a good analogy. You can't take a group of people with ME/CFS, some of whom will be obese, some of whom will have diabetes, some of whom will have other health conditions affecting blood lipids, and compare them with highly selected groups of people where no one is obese and no one has diabetes and in fact no one has any health condition despite being aged over 50, and then assume that any finding of increased rates of dyslipidemia mean anything more than you did not have an appropriate comparison group.
These super healthy people, including the Otherwise Healthy Hypertensives, are much like the Tour de France contestants doing a CPET, they are not normal 50 to 60 year olds.
