Systems Approaches in Public Health

Recognition of the complexity of many public health problems has led to the search for analytic methods capable of capturing more fully than traditional study designs and statistical tests the underlying dynamic processes at work. Similarly, those with an interest in public health interventions have begun to see the limitations of standard methods in understanding the consequences of programs and policies designed to influence population-level health. While there are a number of system science methods with potential to further public health research, there are three methods most often applied: agent-based modeling, social network analysis, and system dynamics modeling. The first discussion reviews both theoretical and practical applications of these three methods in the literature, as each has strengths and weaknesses and is better suited to studying some aspects of complex dynamic phenomena than others. Such a discussion provides practical guidance for those who wish to use these system methods in their own research. Following this, there is a discussion of different perspectives on how these methods relate to traditional behavioral research methods, and how these perspectives affect understanding of and explanation of public health problems. Beginning with a detailed analysis of the three systems methods used in public health and following with a discussion of how different perspectives affect understanding of public health problems sets the stage for the development of a systems model of a complex public health problem. The final section applies these lessons by developing and testing a system dynamics model of type 2 diabetes in the area known as Health Service Region 11. The model framed the problem of diabetes in this region using assumptions implicit within selecting a system dynamics model. The focus was on the effectiveness of physical activity interventions to guide decision-makers in future resource allocation and public health professionals to use appropriate methodologies for complex health problems that traditional linear approaches are unable to capture and thus unable to suggest informed routes for change. The model evaluated different “what if” scenarios of prevention and intervention strategies for reducing prevalence of (and ultimately incidence of) type 2 diabetes

Acute inhalation of hypertonic saline does not improve mucociliary clearance in all children with cystic fibrosis

<p>Abstract</p> <p>Background</p> <p>Little is known of how mucociliary clearance (MCC) in children with cystic fibrosis (CF) and normal pulmonary function compares with healthy adults, or how an acute inhalation of 7% hypertonic saline (HS) aerosol affects MCC in these same children.</p> <p>Methods</p> <p>We compared MCC in 12 children with CF and normal pulmonary function after an acute inhalation of 0.12% saline (placebo), or HS, admixed with the radioisotope ^{99 m}technetium sulfur colloid in a double-blind, randomized, cross-over study. Mucociliary clearance on the placebo day in the children was also compared to MCC in 10 healthy, non-CF adults. Mucociliary clearance was quantified over a 90 min period, using gamma scintigraphy, and is reported as MCC at 60 min (MCC60) and 90 min (MCC90).</p> <p>Results</p> <p>Median [interquartile range] MCC60 and MCC90 in the children on the placebo visit were 15.4 [12.4-24.5]% and 19.3 [17.3-27.8%]%, respectively, which were similar to the adults with 17.8 [6.4-28.7]% and 29.6 [16.1-43.5]%, respectively. There was no significant improvement in MCC60 (2.2 [-6.2-11.8]%) or MCC90 (2.3 [-1.2-10.5]%) with HS, compared to placebo. In addition, 5/12 and 4/12 of the children showed a decrease in MCC60 and MCC90, respectively, after inhalation of HS. A <it>post hoc </it>subgroup analysis of the change in MCC90 after HS showed a significantly greater improvement in MCC in children with lower placebo MCC90 compared to those with higher placebo MCC90 (p = 0.045).</p> <p>Conclusions</p> <p>These data suggest that percent MCC varies significantly between children with CF lung disease and normal pulmonary functions, with some children demonstrating MCC values within the normal range and others showing MCC values that are below normal values. In addition, although MCC did not improve in all children after inhalation of HS, improvement did occur in children with relatively low MCC values after placebo. This finding suggests that acute inhalation of hypertonic saline may benefit a subset of children with low MCC values.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov: <a href="http://www.clinicaltrials.gov/ct2/show/NCT01293084">NCT01293084</a></p

The Value of the Frame: Painting Complexity using Two Chronic Disease Models

As with all chronic diseases, it is now recognized that type 2 diabetes is a complex health issue, the etiology of which involves numerous risk factors operating at different ecological levels of analysis. However, this ecological complexity of the problem seldom manifests itself in the interventions for preventing the problem, which typically focus on changing behavior through universal health education, with the assumption of a homogeneous population. This paper examines the limitations of this way of framing the problem of type 2 diabetes, particularly its failure to capture the way in which this problem emerges because of dynamic interactions between individuals and their environments and how these interactions vary in fundamental ways depending upon the context within which they occur. Specifically, the paper examines how framing of type 2 diabetes in the Lower Rio Grande Valley (LRGV) affects which systems modeling method selects to understand the problem and to help guide policy-makers to ameliorate it. Each systems model has a paradigm characterizing it by a set of fundamental rules and underlying concepts. That is, each method bases on assumptions of how the model should be constructed and the knowledge obtainable from such assumptions. By assuming the model should be constructed in a certain way, the modeler (whether implicitly or explicitly) frames the problem by making assumptions about the phenomenon-of-interest. Choosing to develop any model asserts that the model proscribes to paradigmatic assumptions for how it would contribute something of value) in some capacity (for a purpose), which is ultimately affected by understanding, interpretation, and application of the problem. The paper describes how specific types of systems methods, those using agent-based models (ABMs) and system dynamics models (SDMs), can produce very different ways of understanding the problem of, and the leverage points for, type 2 diabetes in the LRGV. Additionally, it moves beyond simply outlining the general differences in the use and applications of ABM and SDM, to presenting models demonstrating how framing of the problem and model paradigmatic assumptions affect understanding of the problem of type 2 diabetes in the LGRV and its potential leverage points. While the examples are specific to a health problem in a specific community, the significance of such an approach is in its generalizability to how understanding social system behavior depends upon how framing the problem and the paradigmatic assumptions of the modeling method affect our understanding of social systems and public health problems