Population Stratification


Population stratification generates a population distribution by health risk in a given sector or region.

Purpose: define population-level policies and interventions.

Focus: process, which elements are considered? Not the algorithm

This type of stratification is used to generate a map of the distribution of the population by health risk in a given sector or region. It serves the purpose of defining specific policies and interventions at population level. It will also serve for the generation of indicators useful for the follow-up of health outcomes. ACT abstracts from concrete stratification algorithms, which may be different from region to region. Instead, for population stratification we focus on the stratification process, i.e. which elements are included in the stratification. As part of the strategy to perform population-based stratification, we consider five different domains, some of them including several sub-domains 


Conceptual definitions guiding the population-based stratification and the description of the methodological steps followed to obtain population-based indicators


  • Purpose:  primary objective.  What is the purpose of the stratification? {public health purposes, cost savings, enhance efficiency of services,…}
  • Process: the sources of information and the method used to generate the indicators.  When is the stratification performed? {after diagnosis, after hospitalization,…}
  • Frequency:  Time frame and periodicity of the analysis. What is the frequency of stratification {quarterly / yearly / biyearly …}
  • Combination method: How are the elements of the stratification combined? Is <domain/subdomain> considered in the stratification?



information on the epidemiological impact of targeted diseases and their combination (co-morbidities) at population level [Murray, et al., 1997]


  • Severity:  characterizes the state of the disease, based on classifications in international clinical guidelines. HF:  NYHA, COPD: GOLD.
  • Comorbidities: Charlson index.



characterizes the inclusion of the age distribution for population stratification

  • Age domain indicators include age as primary variable, but also age used as part of composed variables to assess the impact of age on survival, healthcare and use of technologies [SIMPHS, 2013].


Deprivation Index

Characterizes poverty in an area

Poverty is related health, education level, availability of means to sustain an healthy lifestyle and social support from the environment and the availability to utilities, e.g. a network. Hence poverty is expected to impact health outcomes and adherence to the programmes [Schuurman, et al., 2007]. 


  • How is the level of deprivation established? {postal code, …}
  • What elements of deprivation are considered? {index, individual elements, …}


Past use of HC resources

Use of healthcare resources within a given period of time are indicators of disease burden on the health system

  • Combinations with other domains may be taken into account, e.g. by disease, disease-severity, comorbidity, age, etc. 


  • Hospitalization: How many hospitalizations occurred? How many related to the target disease?
  • Visits: Frequentation to primary care, home visits, outpatient visits, …
  • Drugs: Indices related with drug consumption, poly-medication, …