20135
Imprinting Variation in the Diagnosis of ASD at Two Specialty Clinics
A large part of the public controversy over ASD stems from the process of diagnosis. Like many other disorders presenting as mental or behavioral rather than immediately physiologic, diagnosis is made on the basis of interpretation against a set of qualitative behavioral criteria in the Diagnostic and Statistical Manual of Mental Disorders (DSM). Intellectually, health care providers must connect specific observed symptoms to abstract criteria. Because the process of inference is opaque, it is unclear whether too few, too many, or simply the wrong people are being diagnosed.
Variation in medical practice among health care providers has been well documented in a number of settings (e.g. Dartmouth Atlas). Applied to the diagnosis of ASD, it is likely that there exists substantial variation in diagnostic practice among health care providers – not only in the structure of the evaluation and the use of specific instruments such as the ADOS, but also in the way in which evidence is assessed against diagnostic criteria.
Sociologists of organizations and professions have studied how technical knowledge may diffuse across individuals or remain localized. The processes studied by sociologists may explain the distribution in diagnostic knowledge and, therefore, differences in diagnostic outcomes both temporally and spatially.
Objectives:
This research examines diagnostic ‘styles’ among health care providers and how these styles are shaped by factors in the health care workplace.
Methods:
We obtain data from a large HMO which operates two clinics specializing entirely in ASD diagnosis. Data include electronic medical records of eight birth cohorts (n=276,395) as well as qualitative data including: direct observation of evaluations at the clinics, 28 interviews, and internal documents describing the history of ASD diagnosis at the HMO. These qualitative data amount to over 200 pages of field-notes and interview transcripts.
Results:
We demonstrate a 30 percentage point difference in ASD diagnosis rates between the two clinics even after controlling for patient characteristics. Methodologically, we accomplish this by (1) including controls in regression models and (2) exploiting a natural experiment based on changes in clinic catchment areas. These results suggest that local organizational, cultural factors may be responsible for the observed diagnostic difference.
Organizational factors are identified and described using qualitative data. We find that the local style of diagnosis was influenced by key individuals at each clinic during the opening of each clinic. These differences in diagnostic styles persists even as these key individuals have left the HMO or have taken on different roles, and despite efforts by organizational leaders to establish a uniform diagnostic process throughout the HMO.
Conclusions:
It is commonly understood that increased diagnosis reflects an increased awareness of ASD, especially in the health care community. The implications of this are underexplored however. Namely, this suggests that variation in knowledge across health care providers and health care organizations shapes the observed patterns of ASD diagnosis. Our research is among the first to study the health care organization directly and muster substantial evidence describing how organizational processes can lead to unexpectedly large differences in diagnosis rates.