Effect/cost

Cost-benefit and cost-effectiveness analyses are commonly used for assessing many types of programmes, both during planning and for evaluation. In the case of food and nutrition programmes, cost-effectiveness is the more suitable approach, since a monetary figure cannot reasonably be put on outcome. This kind of analysis, however, is not often used, and a major advance in these evaluations could be made by much more systematic introduction of the techniques and thinking involved. These do not necessarily depend on accurate data, and indeed some form of cost-effectiveness thinking is implicit in the planning of almost any programme; that there is a level of expenditure per unit of expected outcome that would not be worth it is almost always in the back of someone's mind. We consider that the summary parameter of effect per unit costs (which goes to zero when there is no effect) is a useful start, and this is the one mainly discussed here.

A dose-response type of curve relating effects to cost is likely to apply to intervention programmes. This is familiar in economics (as in total product and utility curves, etc.), but not often considered for nutrition programmes. This means that the relationships show in figure 1.2. (see

FIG. 1.2. Effect/Cost Curves (scale only for illustration). A: Effect. B: Effect/cost.) are likely to apply. Probably there is as yet insufficient data to put a scale on the X axis, but some research on existing data might allow hypotheses to be put forward. In this hypothetical example, a cost per head of the target population of around $13 gives the maximum cost-effectiveness calculated as number of cases prevented per thousand dollars (fig. 1.2. B); but this rate of expenditure gives less than the maximum overall effect (fig. 1.2. A). The two curves are directly related: for example at $10 per head expenditure, if 100 cases per thousand population are prevented (A), this is 100 cases per $10,000. or 10 cases per thousand dollars (B). The effect/cost in B for any value of cost per head is equal to the total effect as can be read off in A, divided by the corresponding cost per head. Put another way, the height of the curve in B at any value of cost per head is the slope of the line joining the origin to the corresponding point on the curve in A.

One important advantage of such methods would be to allow assessment of whether the level of effort in a programme is at least in the range in which an outcome effect could be expected, taking account also of the level of malnutrition in the target group. It is our impression that often a programme could reasonably be expected to have little effect because the level of expenditure is too low relative to the expected doseresponse. This idea has been referred to as "situation assessment" (see [5]).

Effects per unit cost may also be used to define the extent to which an accurate assessment of outcome is needed. For example, (using relationships similar to those in figure 1.2.) it might be postulated that a change from 20 per cent prevalence to 10 per cent prevalence after the treatment is the maximum feasible (e.g. from

200 malnourished in a population of 1,000 to 100 malnourished) at a cost of say $10 per head (i.e. $10,000 for the population of 1,000). This is equivalent to proposing an effect per unit cost of 10 cases prevented or rehabilitated per $1,000. Clearly, this should have been regarded as good value for money at the stage of planning the project. Similarly, no change would mean that effect per cost was zero. Somewhere between these two, a level of change could be set below which it was regarded that the programme's resources were not being well spent for reasons which could relate to targeting, type of activity. adequacy of delivery. etc. For example; rehabilitation of 5 cases per $1,000 could be regarded as the minimum effect/cost ratio acceptable. This means that the maximum acceptable post-programme prevalence is 15 per cent (i.e. a maximum of 150 malnourished in the population of 1,000). In this case, it is only necessary to know whether the with-programme prevalence is above or below the adequacy cut-off point of 15 per cent.