Diagonal Health Care: Clever Cartoons Hide the Benefits of Complementarity and the Costs of Unbalanced Provider Incentives

April 22, 2008
A paper by Gorik Ooms of Médecins Sans Frontières Belgium and co-authors introduces a new metaphor to the discussion of policy towards developing country health systems: "diagonalization." This word adds a useful image to the still unresolved and increasingly sterile debate between advocates of "vertical" and "horizontal" health programs. For those from outside the health sector (is anyone like that reading this blog?), a horizontal program is one which attempts to provide the population with access to generalist health care practitioners who can attempt to diagnose any patient, to treat some and refer others to more highly trained or specialized providers at "higher levels" of a health care referral structure. In contrast, a vertical program is one which is designed to deliver a single package of interventions, often aimed at a single disease or at a group of diseases that can all be addressed by that package. In order to dramatize the distinction between these two extreme types of support to a health care system, Ooms et al. offer novel cartoons to show the advantages and disadvantages of each system. The horizontal philosophy of health system support is illustrated by the following picture, in which the support is shown as a layer of orange sand labeled "aditional [sic] health expenditure" which only succeeds in elevating total public health care spending from US$10 to US$20, not high enough to reach the US$40 target set by the commission on macroeconomic and health. Since no part of the system extends above water, the implication is that, in a "horizontal" health system, fish may swim, but patients will drown. In contrast, the vertical system is shown as a column of sand all piled precariously in one spot of the system. By depicting the vertical program as extending above the "water line" of US$40, the authors are suggesting that, at least on this "island of sufficiency," patients can receive effective care or public health programs, at least for this one set of problems, because public expenditure per capita (however defined) is greater than the "water line." The problem depicted by the cartoon is that the structure supporting the island is undermined by erosion from the surrounding underfunded "swamp." The authors imply that a vertical program can survive for a short time in the "swamp" of an inadequately funded health care system, but forces that arise from the contrast between the inadequate funding for the rest of the system and the relatively luxurious funding of the vertical program lead to the eventual destruction of the vertical program. From these diagrams it is clear that the authors' sympathies lie more with vertical than with horizontal programs. According to the cartoons, a vertical program temporarily creates an island of sufficiency, whereas the horizontal program is a total failure. While vertical programs certainly have their advantages, to suggest that they prevent drowning while horizontal programs never do is unfair to horizontal programs. A better model is one in which both horizontal and vertical programs produce benefits, but using different technologies. Years ago I was caught in a battle between an ardent advocate of each type of health care during a frustrating mission to Mauritania. Inspired by that experience, I subsequently wrote a paper arguing that the advantage of a horizontal program should be in the possibility of technical complementarity, both for the producer and for the consumer, between different health care services located in the same building. In economics terms, a horizontal program might be a more cost-effective intervention than a vertical one if it achieves sufficient "economies of scope" by offering multiple health care services from the same location. These cartoons are unable to capture the benefits of economies of scope. The diagrams are biased in favor of vertical programs in another hidden way. The orange sand crumbling from the vertical sides of the island in panel (b) and sifting down to the ocean floor only seems to elevate the level of funding of the surrounding horizontal program - not to actively harm it. In fact, the open question that needs to be resolved is whether AIDS treatment programs and other vertical programs, by paying higher salaries than the surrounding system, actually undermine the surrounding system. Perhaps a reader of this blog can suggest an alternative cartoon that could depict this possibility. The innovation that Ooms et al are introducing is the idea of a so-called "diagonal" support program, which they illustrate with a third clever diagram shown in Panel (c). Their cartoon suggests that vertical programs can only be sustained if they have a broad supporting structure which funds enough of the surrounding structure of the health system to allow the vertical program to function indefinitely. If orange sand is equated to financing, the picture suggests that a diagonal program will require a lot more funding than a vertical program. But how much more? Engineers refer to the angle between the ground and the stable slope of a pile of sand as the "angle of repose." The smaller the angle of repose of the diagonal health program, the more sand will be required to sustain the "island of sufficiency" and the more the program will cost. An advocate of horizontal programs might argue that the only stable angle of repose is zero, with public health system spending topped up until the whole health care system is equally funded at a level which removes the special nature of the vertical programs. Palm trees everywhere. Thus a challenge to those who would propose a "diagonal" health program is to describe which systems should be strengthened to support their favorite vertical program - and by implication which systems can be excluded.


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