Cited by 176HIV/AIDS Research and InterventionsHIV, Drug Use, Sexual RiskHealth disparities and outcomes

The DOI matches its Crossref record; 65 of the 67 references it cites were found in a registry or an index; none of the 27 sources its claims cite is checked for support yet.

Syndemics and Health Disparities: A Methodological Note

Open access

Abstract

In the theory of syndemics, diseases are hypothesized to co-occur in particular temporal or geographical contexts due to harmful social conditions (disease concentration) and to interact at the level of populations and individuals, with mutually enhancing deleterious consequences for HIV risk (disease interaction). Since its original elaboration more than 20 years ago, the epidemiological literature on syndemic problems has followed a questionable trajectory, stemming from the use of a specific type of regression model specification that conveys very little information about the theory of syndemics. In this essay we critically review the dominant approaches to modeling in the literature on syndemics; highlight the stringent assumptions implicit in these models; and describe some meaningful public health implications of the resulting analytical ambiguities. We conclude with specific recommendations for empirical work in this area moving forward.

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

This methodological essay argues that common syndemics analyses using a summed count of psychosocial and structural problems cannot establish synergistic interaction, because a positive count coefficient can occur even under purely additive effects. It recommends using fully saturated interaction models to test syndemic theory and discusses implications for intervention design.

Key findings

  • In the systematic review cited (Tsai & Burns), 27 of 40 studies (68%) showed co-occurrence via Venn diagrams, correlation matrices, or odds ratio matrices, and 31 of 40 (78%) used a sum score of problems.
  • Algebraically, the sum-score coefficient can be positive and significant when the true data-generating process is additive; the sum score imposes equal effects across problems rather than testing synergy.
  • The saturated model with all product terms is the only specification that flexibly conveys interaction; the continuous sum-score model should be abandoned, and the ordinal sum-score model still assumes two-way product terms are zero.
  • Public health consequences include unclear excess concern for true syndemics, missed targeted intervention opportunities, and the multi-component “treatment package” not necessarily being optimal; alternatives include sequential, collateral, or fractional factorial strategies.

Methods

  • Critical methodological essay, not an empirical study; uses a hypothetical cohort of homeless and marginally housed women with violence, food insecurity, mental illness, and a binary HIV-related outcome.
  • Compares linear regression specifications: additive main-effects model, fully saturated interaction model, continuous sum score, and ordinal sum score; draws on a prior systematic review of 40 syndemics studies.
  • Main analysis is algebraic demonstration and discussion of assumptions, sample size/power, and recommendations.

Limitations

  • Stated: small samples may prevent full interaction estimation and yield wide confidence intervals; collinearity among co-occurring problems worsens imprecision; type II error may miss true syndemics or understate the number of interacting epidemics. Authors counter that nearly half of reviewed studies could fit saturated models by conventional rules.
  • Stated: sum-score specifications impose strong assumptions (e.g., equal main effects or zero two-way interactions) that are rarely justified by theory.
  • Evident from text: no new data are analyzed; the illustration is hypothetical and the critique relies on prior review and selected examples, so the recommendations are not empirically validated here.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1007/s10461-015-1260-2

Cites

65 of 65 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

0 of 27 cited sources checked · 0 supported · 0 flagged

Show all 25 claims

  • Probably not a substantial claim. 20
  • It may state two separate claims as one. 15
29 of 29

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Category indicators do not sum to one for the reference group

    Minor

    For a person with zero problems, all three indicators are zero, so their sum is zero rather than one. The paper explicitly includes zero problems as the reference category.

1 of 1

Citations

Cites

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Show all 67 references

2 of the 67 references couldn’t be matched to a known paper.

Research works printed but not linked: 3

  1. Batchelder AB. Psychosocial syndemics of women living with and at-risk for HIV/AIDS (dissertation). New York: Yeshiva University; 2012.
  2. Ashenfelter O, Haveman RH, Riley JG, Taylor JT. Editorial statement. Am Econ Rev. 1986;76(4):v.
  3. Bernanke BS. Editorial statement. Am Econ Rev. 2004;94(1):404.

Cited by

Sorted by citations

Items 101–175 of 175

Metadata

Authors
Tsai, A. C., & Venkataramani, A. S.
Affiliations
Harvard University (US)
Corresponding author
Tsai, Alexander C.
Venue
AIDS and Behavior
Published
2015-12-12
Volume
20
Issue
2
Pages
423-430
ISSN
  • 1090-7165 (ISSN-L)
  • 1573-3254
OpenAlex
W2191960283
Cited by
176
References
67
Citations by year
2026: 11 · 2025: 17 · 2024: 25 · 2023: 15 · 2022: 27 · 2021: 22 · 2020: 23 · 2019: 10 · 2018: 10 · 2017: 6 · 2016: 3
FWCI
4.90
Type
journal article
Language
en
Open access
Locations
  • AIDS and Behavior (publishedVersion)
  • PubMed (publishedVersion)
  • Europe PMC (PubMed Central) (acceptedVersion)
  • PubMed Central (acceptedVersion)
Funders
National Institute of Mental Health (K23MH096620)
Topics
  • Health Sciences › Medicine › Infectious Diseases › HIV/AIDS Research and Interventions
  • Health Sciences › Medicine › Epidemiology › HIV, Drug Use, Sexual Risk
  • Social Sciences › Health › Health disparities and outcomes
Keywords
syndemic, health disparities, disease interaction, HIV risk, regression model specification, social conditions, epidemic modeling, public health implications
MeSH terms
Public Health, Regression Analysis, Social Environment, Social Problems, HIV Infections, Health Status Disparities

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