Clinical Investigation
Outcomes, Health Policy, and Managed Care
Linking inpatient clinical registry data to Medicare claims data using indirect identifiers

https://doi.org/10.1016/j.ahj.2009.04.002Get rights and content

Background

Inpatient clinical registries generally have limited ability to provide a longitudinal perspective on care beyond the acute episode. We present a method to link hospitalization records from registries with Medicare inpatient claims data, without using direct identifiers, to create a unique data source that pairs rich clinical data with long-term outcome data.

Methods and Results

The method takes advantage of the hospital clustering observed in each database by demonstrating that different combinations of indirect identifiers within hospitals yield a large proportion of unique patient records. This high level of uniqueness also allows linking without advance knowledge of the Medicare provider number of each registry hospital. We applied this method to 2 inpatient databases and were able to identify 81% of 39,178 records in a large clinical registry of patients with heart failure and 91% of 6,581 heart failure records from a hospital inpatient database. The quality of the link is high, and reasons for incomplete linkage are explored. Finally, we discuss the unique opportunities afforded by combining claims and clinical data for specific analyses.

Conclusions

In the absence of direct identifiers, it is possible to create a high-quality link between inpatient clinical registry data and Medicare claims data. The method will allow researchers to use existing data to create a linked claims-clinical database that capitalizes on the strengths of both types of data sources.

Section snippets

Data sources and patient populations

We used 2 inpatient databases in this study, neither of which made direct patient identifiers available. First, we used data from the Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients With Heart Failure (OPTIMIZE-HF) registry.5 This registry contains information on eligible hospitalizations from hospitals that participated voluntarily in the OPTIMIZE-HF quality improvement program. Eligible hospitalizations included those for which heart failure was the primary cause

Discussion

Although previous work has been done to link different databases to Medicare claims data,6, 7, 8 these efforts required direct identifiers like patient name or Social Security number. In this article, we describe and demonstrate a method that enables researchers to identify a high proportion of clinical registry database hospitalizations in 100% Medicare inpatient claims data without direct patient identifiers. We found that using combinations of nonunique fields commonly available in both

Conclusions

In the absence of direct identifiers, it is possible to create a high-quality link between inpatient clinical registry data and Medicare claims data. The method allows researchers to leverage existing data to create a linked claims-clinical database that capitalizes on the strengths of both types of data sources. Combined databases such as these are important at a time when there is otherwise little infrastructure to answer important safety, efficacy, and other clinical questions for large

Acknowledgements

We thank Damon M. Seils, MA, Duke University, Durham, NC, for assistance with the manuscript preparation. Mr Seils did not receive compensation for his assistance apart from his employment at the institution where the study was conducted.

References (14)

  • FonarowG.C. et al.

    Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients With Heart Failure (OPTIMIZE-HF): rationale and design

    Am Heart J

    (2004)
  • FonarowG.C. et al.

    Influence of a performance-improvement initiative on quality of care for patients hospitalized with heart failure: results of the Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients With Heart Failure (OPTIMIZE-HF)

    Arch Intern Med

    (2007)
  • MehtaR.H. et al.

    Recent trends in the care of patients with non–ST-segment elevation acute coronary syndromes: insights from the CRUSADE initiative

    Arch Intern Med

    (2006)
  • PetersonE.D. et al.

    Association between hospital process performance and outcomes among patients with acute coronary syndromes

    JAMA

    (2006)
  • TuJ.V. et al.

    Impracticability of informed consent in the Registry of the Canadian Stroke Network

    N Engl J Med

    (2004)
  • BradleyC.J. et al.

    Medicaid, Medicare, and the Michigan Tumor Registry: a linkage strategy

    Med Decis Making

    (2007)
  • LillardL.A. et al.

    Linking Medicare and national survey data

    Ann Intern Med

    (1997)
There are more references available in the full text version of this article.

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This work was supported by grant U18HS10548 from the Agency for Healthcare Research and Quality (Rockville, MD) and a research agreement between GlaxoSmithKline (Research Triangle Park, NC) and Duke University (Durham, NC). Dr Hernandez is a recipient of an American Heart Association Pharmaceutical Roundtable grant (0675060N). Drs Curtis and Schulman were supported in part by grants U01HL066461 from the National Heart, Lung, and Blood Institute and R01AG026038 from the National Institute on Aging. Dr Fonarow is supported by the Ahmanson Foundation (Beverly Hills, CA) and the Corday Family Foundation (Los Angeles, CA). The OPTIMIZE-HF registry is registered at clinicaltrials.gov as study number NCT00344513.

David J. Cohen, MD, MSc served as guest editor on this manuscript.

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