Health Measurement Model-Bringing a Life Course Perspective to Health Measurement: The PRISM Model

Abstract

Health is a multidimensional concept that is challenging to measure, and in the rapidly evolving developmental changes that occur during the first 21 years of human life, requires a dynamic approach to accurately capture the transitions, and overall arc of a complex process of internal and external interactions. We propose an approach that integrates a lifecourse framework with a layered series of assessments, each layer using a many to many mapping, to converge on four fundamental dimensions of health measurement-Potential, Adaptability, Performance, and Experience. The four dimensions can conceptually be mapped onto a plane with each edge of the resulting quadrilateral corresponding to one dimension and each dimensions assessment calibrated against a theoretical ideal. As the plane evolves over time, the sequential measurements will form a volume. We term such a model the Prism Model, and describe conceptually how single domain assessments can be built up to generate the holistic description through the vehicle of a layer of Exemplar Cases. The model is theoretical but future work can use the framework and principles to generate scalable and adaptable applications that can unify and improve the precision of serial measurements that integrate environmental and physiologic influences to improve the science of child health measurement.

Keywords: childhood; health measurement; life course health development; longitudinal study; measurement models.

Figure 1

The four dimensions of health measurement form a planar shape that evolves through the dimension of time. If all four dimensions are balanced, the plane can be represented by a square and the temporal trajectory would be a quadrilateral cuboid, shown on the left. A feasible trajectory of an actual person is on the right showing changes in proportions over time.

Figure 2

On the left, Improving phenotype is represented by the prism in the shape of an inverted trapezoid, with its resulting volume. An example would be a premature infant with lung disease that normalizes over time with effective intervention. In the middle, the Worse before Better phenotype is represented by an hourglass shape. An example may be a neurological condition that deteriorates until an effective intervention is developed that reverses the trend. On the right, a Worsening phenotype is represented by a pyramidal prism. An example of the Worsening phenotype would be a chronic, multisystem disease diagnosed in infancy such as Tay-Sachs disease that is not amenable to new therapeutic options.

Figure 3

Domain Working Groups (DWG) developed specific measures in the context of the four dimensions of health measurement so that a functional continuity could be established through mapping from single measurements into higher order descriptions.

Figure 4

Many to many mapping among system components. The Domain Workgroups propose specific assessments that collectively form a library of direct measures that are age and developmentally appropriate across all six of the assessment domains. From the library of unique assessments, a visit schedule is generated so that each visit is as complete as feasible but not burdensome. The output from the direct assessments is combined with external administrative data and mapped in a series of many to many relationships to the catalog of drivers. Once values are determined for the relevant drivers, those values are subsequently mapped via a many to many process to the Exemplar Cases, which are in turn mapped to four health measurement dimensions.

Figure 5

Depicts a perspective on the Exemplar Case approach. The focal lens represents the influence of the interacting biological, psychosocial, and physical environments. Over time, their dynamic interaction results in the overlapping lenses of nine Exemplar Cases. These lenses support an approach to measurement that requires determining the biological, psychosocial and physical drivers that interact to predict each of the nine Case outcomes at age 21. This measurement strategy provides the ability to prioritize measurements and identify potential gaps in measurement.