Risk for Hospital Contact With Infection in Patients With Splenectomy

A Population-Based Cohort Study

  1. Reimar W. Thomsen, MD, PhD;
  2. W. Marieke Schoonen, MSc, PhD;
  3. Dóra K. Farkas, MSc;
  4. Anders Riis, MSc;
  5. Jacob Jacobsen, MSc;
  6. Jon P. Fryzek, PhD; and
  7. Henrik Toft Sørensen, MD, DMSc
  1. From Aarhus University Hospital, Aalborg, Denmark, and Amgen, Uxbridge, Middlesex, United Kingdom, and Thousand Oaks, California.

    Abstract

    Background: Splenectomy has been associated with increased risk for infection.

    Objective: To assess the magnitude and duration of risk for hospital contact with infection associated with splenectomy.

    Design: Population-based cohort study.

    Setting: Denmark.

    Patients: All 3812 persons in Denmark who underwent splenectomy from 1996 to 2005. Splenectomized patients were matched to 3 comparison cohorts: the general population, appendectomized patients, and unsplenectomized patients with indications for splenectomy.

    Measurements: Relative risks were assessed for hospital contact involving any infection, pneumonia, and microbiologically confirmed bacteremia among 3812 splenectomized patients and their matched comparisons, during different follow-up periods and after regression analysis for confounder adjustment.

    Results: The adjusted relative risk for any hospital contact with infection was highest within 90 days of splenectomy: 10.2% vs. 0.6% among general population comparisons (adjusted odds ratio, 18.1 [95% CI, 14.8 to 22.1]) and 10.2% vs. 4.2% among appendectomized patients (adjusted odds ratio, 2.4 [CI, 2.1 to 2.8]). The hazard of infection was 4.6-fold (CI, 3.8 to 5.5) higher in splenectomized patients than in general population comparisons from 91 to 365 days after splenectomy and 2.5 times (CI, 2.2 to 2.8) higher more than 365 days after splenectomy. The risks were similar for pneumonia and were higher for bacteremia. Markedly increased risks were also found when compared with those of appendectomized patients. Modest increases in infection risk were seen with splenectomy matched-indication comparisons (adjusted 90-day odds ratio, 1.7 [CI, 1.5 to 2.1]; hazard ratios, 1.5 [CI, 1.2 to 1.8] from 91 to 365 days after splenectomy and 1.2 [CI, 1.1 to 1.4] beyond 365 days after splenectomy). Relative risks for infection were highest in patients who had splenectomy because of hematologic disorders.

    Limitation: Increased surveillance among splenectomized patients may have affected the findings.

    Conclusion: Splenectomy is associated with increased long-term risk for infections involving hospital contact.

    Primary Funding Source: Amgen, Clinical Epidemiological Research Foundation at Aarhus University, and Karen Elise Jensen Foundation.

    Article and Author Information

    • Grant Support: By Amgen, the Clinical Epidemiological Research Foundation at Aarhus University, and the Karen Elise Jensens Foundation.

    • Potential Conflicts of Interest: Employment: W.M. Schoonen (Amgen), J.P. Fryzek (Amgen). Stock ownership or options (other than mutual funds): W.M. Schoonen (Amgen), J.P. Fryzek (Amgen).

    • Reproducible Research Statement: Study protocol and statistical code: Available from Dr. Sørensen (e-mail, hts{at}dce.au.dk). Data set: The Danish Data Protection Agency does not allow transferral of the project data to external research institutions. Most of the source data are stored with Statistics Denmark and can be made available for analysis from www.dst.dk/research.

    • Requests for Single Reprints: Reimar W. Thomsen, MD, PhD, Department of Clinical Epidemiology, Aarhus University Hospital, Aalborg Hospital Science and Innovation Center, Søndre Skovvej 15, DK-9000 Aalborg, Denmark; e-mail, r.thomsen{at}rn.dk.

    • Current Author Addresses: Dr. Thomsen: Department of Clinical Epidemiology, Aarhus University Hospital, Aalborg Hospital Science and Innovation Centre, Søndre Skovvej 15, DK-9000 Aalborg, Denmark.

    • Dr. Schoonen: Amgen, 1 Uxbridge Business Park, Sanderson Road, Uxbridge, Middlesex UB8 1DH, United Kingdom.

    • Ms. Farkas, Mr. Riis, Mr. Jacobsen, and Dr. Sørensen: Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Alle 43-45, DK-8200 Århus Nord, Denmark.

    • Dr. Fryzek: Amgen, One Amgen Center Drive, Thousand Oaks, CA 91360.

    • Author Contributions: Conception and design: D.K. Farkas, J. Jacobsen, R.W. Thomsen, W.M. Schoonen, A. Riis, J.P. Fryzek, H.T. Sørensen.

    • Analysis and interpretation of the data: R.W. Thomsen, W.M. Schoonen, D.K. Farkas, A. Riis, J. Jacobsen, J.P. Fryzek, H.T. Sørensen.

    • Drafting of the article: R.W. Thomsen, W.M. Schoonen, J.P. Fryzek.

    • Critical revision of the article for important intellectual content: D.K. Farkas, J. Jacobsen, R.W. Thomsen, W.M. Schoonen, J.P. Fryzek, H.T. Sørensen.

    • Final approval of the article: R.W. Thomsen, W.M. Schoonen, D.K. Farkas, A. Riis, J. Jacobsen, J.P. Fryzek, H.T. Sørensen.

    • Administrative, technical, or logistic support: D.K. Farkas, J. Jacobsen.

    • Statistical expertise: W.M. Schoonen, D.K. Farkas, A. Riis, J. Jacobsen, J.P. Fryzek.

    • Collection and assembly of data: A. Riis.

    Responses to this article

    • Impact of Splenectomy on Subsequent Infections
      • Tetsuji Fujita
      Ann Intern Med published online November 10, 2009

    Summary for Patients

    • Summaries for Patients:Risk for Hospitalization for Infection in Patients Who Have Had Splenectomy Ann Intern Med October 20, 2009 151:I-42; doi:10.1059/0003-4819-151-8-200910200-00003
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