Opinion: Pareto’s Curse

Four out of five patients at a primary health care center could benefit from counseling but only one out of five is referred. Of those referred 20 percent cancel their appointment or just do not show up. In that group 80 percent manages as good on their own and the other 20 percent need counseling the most. Of those who come to counseling 80 percent needs help to understand and cope with their current situation whereas 20 percent are in the need of a broader approach. In the group that needs a broader approach 80 percent is best treated in the primary care with an eclectic stance while the other 20 percent for the best is referred to secondary psychiatric care.

The group that is accepted for RCT (randomized controlled trial) studies is found among the 80 percent of the patients with the need of a broader approach of the 20 percent of the patients in counseling. In that population 80 percent is not accessible for the scientists (due to life et cetera). The other 20 percent is subject to research. Approximately 20 percent of this group of 20 percent are the very patients that are part of the RCT studies (they have accepted to be randomized for CBT (cognitive behavioral therapy) or TAU (treatment as usual), they have allocated time for all tests, they have showed up for all sessions and done their homework, and they have taken part of the follow ups. Lately it has been shown that internet based CBT and group based CBT is as god as CBT with physical sessions. This research is based on the group of 20 percent of the population that accept and endure physical sessions CBT.

Pareto’s law is an empirically based statement that identifies a 80/20 relation in various situations. At a primary health care center, for example, 20 percent of the patients stands for 80 percent of all the appointments.

When the healthcare is under pressure from stakeholders to produce more and more evidence based appointments there is a risk that Pareto’s law collapses into what I call Pareto’s curse. In this particular case evidence based practice translates into CBT which translates into good practice. CBT is good. But without individually customized CBT and without more than one line of treatment only 20 percent of 20 percent of 80 percent of 20 percent of those who come for counseling will benefit from the treatment. That is 0,64 percent or one patient out of 156 patients needing counseling.

To understand why this threatens healthcare systems we have to look at Goodhart’s law. Goodhart’s law can be formulated as “When a measure becomes a target, it ceases to be a good measure.” The evidence based practice movement initially wanted to give research its natural place next to clinical experience and the patients preferences. This measure then became the target.

To overcome Pareto’s Curse we must return to Pareto’s Law and do what is best in each situation.

(A counselor the other day went with her daughter to a primary healthcare clinic for teenagers for a first meeting with a psychologist. The daughter spent 80 percent of the session filling in forms and talked with the psychologist for 20 percent of the session. The daughter decided to not return.)

(Note, this is only a problem in 80 percent of 20 percent of the world’s countries.)

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