So, here goes for yet another summary, based on my current understanding.
I'm sure that I'm going to regret posting this, as I'll probably find out it's a load of rubbish later.
So please take anything from this that might be useful, but don't rely on it for accuracy.
This is an attempt to explain the basis of the paper, and the results.
First, it's important to note that Healthcare costs include the costs of administering the therapies (APT,CBT,GET,SMC) along with other misc healthcare costs, and that Societal Costs include the Healthcare costs.
So the Societal Costs indicate the overall total costs or savings, consisting of Healthcare costs (including paying for administering the therapies), lost Employment/Production costs, and informal care costs. (The itemised costs, for each of these overall costs, are listed in Table 3).
So, if there is an overall saving for societal costs, it means the savings include the costs of administering the therapies.
CBT+SMC and GET+SMC do not have significantly lower overall (societal) costs compared with SMC alone, but they are lower, according to the adjusted Totals in Table 3. It's important to note that the primary results of the study were not based on the overall, or total, costs and savings. The primary results are based on costs 'per individual improved', or costs per the number of QALYs gained per individual. A QALY is simply a measure of quality of life, based on the answers to a short questionnaire.
Table 3 shows all the costs before and after treatment started (pre-randomisation, and post-randomisation.)
Table 6
Table 6, compares the changes in the costs shown in Table 3 (the changes in the periods before and after treatment started). Table 6 compares the changes between the various therapy groups (e.g. CBT+SMC vs SMC.)
Table 6 is the best illustration of the results, although it seems that Table 6 is based on average costs and effects per person, whereas the main results have been calculated sightly differently, using a method called 'bootstrapping' which uses all the individual costs and effects of each person (not the averages) to calculate the primary results of the paper.
Table 6 shows the 'incremental' changes for each therapy. This means that the changes over and above the changes for SMC are shown. (i.e. the difference between CBT+SMC vs SMC alone.)
Table 6 is split into three categories: 1. QALYs. 2. Fatigue (Chalder Fatigue.) 3. Disability (SF-36 Physical Function.)
Looking at each of the rows in the QALY section:
"Incremental effect" indicates how many QALYs were gained per individual as a result of each therapy. (i.e. incremental QALYs gains as a result of CBT and GET. Not the QALYs gained for CBT+SMC.) (Remember that a QALY is a subjective measure of quality of life, based on a questionnaire.) The gains in QALYs were based on measurements taken at baseline and at 52 weeks.
The "incremental healthcare cost" shows the mean incremental healthcare costs per person, for each therapy. (Incremental = costs over and above costs for SMC. i.e. CBT+SMC vs SMC)
"ICER (Healthcare)" shows the mean healthcare cost per QALY gained for each individual. This is the healthcare cost, for each therapy, in order for each individual to gain a QALY, including costs to administer the therapies in order to gain QALYs.
"Incremental Societal cost" shows the mean incremental (overall) societal costs/savings (a negative value is a saving), per individual. Remember that societal costs include healthcare costs, so if societal costs have a negative value, then there is a net overall saving per individual, even taking into account costs for administering the therapies. The (statistically insignificant) societal cost savings seen for CBT and GET are based on improved lost employment costs, and improved informal care costs.
"ICER (societal)" indicates whether CBT+SMC etc., have overall costs or savings, compared with SMC alone, per QALY, per individual. The use of the term "dominant" indicates that there are cost savings for CBT+SMC, compared with SMC alone, and for GET+SMC, compared to SMC alone. (SMC is the control group, and Table 6 indicates the 'difference from SMC', or the incremental costs/savings for each of the therapies, once the changes in the SMC control group have been factored out of each of the therapy groups.) So the results given under "ICER (societal)" indicate that, compared to SMC alone, CBT+SMC and GET+SMC make savings for society for each QALY gained per individual. (And maybe it could be said that, compared to 'no treatment', CBT and GET make savings for society for each QALY gained per individual. But I don't think that it is appropriate to say this.)
In the QALY section, ICER (healthcare) and ICER (societal) illustrate the basis of the primary results of this paper.
(The actual primary results are calculated slightly differently to Table 6, as explained earlier.) The other two sections in Table 6 (fatigue and disability) are said to support the findings of the QALY section.
ICER (healthcare) shows the healthcare cost per QALY gained (i.e. costs to administer the therapies plus various other healthcare costs). The paper says that the NHS values a QALY at £30,000. This means that the improvements in quality of life, measured in QALYs, have been costed at £30,000 per QALY. (I don't know how the NHS calculate this.) So if one QALY can be gained at a healthcare cost of less than £30,000 then apparently the NHS consider it worth administering the therapy.
ICER (healthcare) indicates that CBT and GET gained QALYs at a cost of less than £30,000 each, hence the main conclusion of the paper that CBT and GET are cost effective.
This is the main basis of the conclusions of the paper, but Figures 1 & 2 demonstrate the primary results which are calculated slightly differently from Table 6.
If should be noted that where the paper says that CBT and GET are more cost effective than SMC, they are being misleading and inaccurate. SMC is the control group, and the paper does not, and cannot, make a judgement on the cost effectiveness of SMC, because a control group is used to factor out any natural fluctuations over time etc.
If a direct comparison is made between CBT only and SMC alone, and GET only and SMC alone, then SMC is always more cost effective.
Parts of the paper are worded and labelled in a confusing and misleading way.
Another way to demonstrate this is that, instead of making comparisons between SMC+CBT and SMC, etc, I think it might be less confusing to think about CBT and GET being more cost effective than 'no treatment', because the paper looks at the relative changes comparing CBT+SMC vs SMC, and GET+SMC vs SMC. But I don't think that it is actually appropriate to say that there is a comparison between each of the therapies and 'no treatment'.
There's not a lot of clarity in the cost-effectiveness paper, but it does use appropriate wording in at least one section:
"The resultant ICER indicates the cost of one extra person achieving such a change as a result of using APT, CBT or GET in addition to SMC compared to SMC alone."
In other words: "CBT and SMC used in combination, compared to SMC alone."
ICER (societal) indicates that societal (overall) cost savings are seen for CBT+SMC and GET+SMC, compared with SMC alone, per QALY gained per individual. (i.e. compared to 'no treatment', CBT and GET make overall cost savings for society for each QALY gained per individual.)
The incremental mean societal savings per individual (not per QALY per individual), for CBT and GET, were not statistically significant, and I'm not sure if it is clear if the savings per QALY, per individual, are significant, from the details given in the paper. I think that the actual ICER societal savings per QALY per individual are not given, but my rough calculations make it: CBT = -£9,431, GET = -£5,743. (These are the savings for CBT+SMC and GET+SMC compared to SMC alone.)
The fatigue and disability sections in Table 6, show the overall costs and savings per person improved, based on the primary outcomes of the original PACE Trial paper.
They are said to support the primary results illustrated in the QALY section of Table 6.
Details for changes in welfare benefits and private financial payments (income protection insurance and private pensions) are given, but are excluded from the calculations for the main results. It's not clear why.