Quantification and Forecasting

Quantifying the requirements of health products is one of the most important parts of the procurement and supply chain management cycle. If needs are underestimated, it could lead to insufficient supply, stock outs and ultimately patient treatment disruption. If needs are overestimated, resources may be wasted, as health products have a limited shelf-life and over-stocking increases the risk of expiry.

The determination of health product needs is typically based on one of the following quantification methods:

• Consumption: This method is used if the products are being procured for well-established treatment protocols or uses that have records of past consumption and predictable needs. The consumption method forecasts future needs by relying on past use and is adjusted for stock-outs, expiration of overstocked items and projected changes in utilization.
• Morbidity: This method is used for new medicines or programmes with no historical use data, or for programmes with an expected change of consumption, due – for example – to an increase of patients (number of patients on ART usually increase as new HIV positive patients get enrolled). Initial projections must be based on morbidity data if consumption data is absent. The method estimates the needs based on the expected number of attendances, the prevalence or incidence of disease, and standard treatment guidelines for the health problem that is to be treated.

All projections must take into account the health service capacity.

Accurate quantification of needs for health products in a given country and context requires access to technical information about the recipient country’s treatment programme and epidemiological data. Supply chain, procurement and disease programme specialists should work together in quantifying and validating the products and quantities to be procured.

The key information and data that should be reviewed to determine products and quantities includes:

• National testing, treatment, and care guidelines for the relevant disease and/or protocols of care at time of submission. Note: If the protocols are under revision, consider a transition plan (e.g. change of regimens, introduction of new paediatric formulations, shortened regimens for MDR, roll-out plan and timeliness, supply chain preparation for the transition)
• Diagnostic testing and monitoring algorithm(s) for the relevant disease
• Baseline information, programme capacity and disease specific scale-up plans/targets for a defined period
• Existing investments in health equipment (e.g., GeneXpert): national strategy and information on use across programmes, long-term sustainability strategy for routine maintenance, repairs and services, and procurement of reagents and consumables
• National supply plan that reflects the schedule of all agreed financial (or product) contributions to the national needs over the grant period
• Integrated stock status report showing stock-on-hand and purchase order quantities (pipeline) for key commodities covering all sources, where applicable
• Buffer stock and rationale for inclusion in the calculations
• Country population and target population, broken down by age/weight

In some countries, comprehensive epidemiological data is not available, particularly in low-income countries or countries experiencing civil or national conflict. Countries experiencing conflict may have a high rate of migration, displaced persons and returnees and may not be able to obtain accurate population estimates. If some of the aforementioned information is not readily available, countries should quantify based on the information available, then closely monitor consumption rates, adjusting the forecast as more information becomes available.