Letters to the Editor: Letters & Announcements
We welcome the comments of Drs. Shander, Javidroozi, and Goodnough, leaders in perioperative management of anemia, on the subject of screening for anemia (1). They have cited evidence that anemia is important in patients who are hospitalized, have cancer, congestive heart failure, cardio-renal-anemia syndrome, or are undergoing chemotherapy or moderate to high-risk surgery. It is necessary to be vigilant for all anemia, including asymptomatic mild anemia, in higher-risk patients. The threshold of hemoglobin (Hb) <9 g/dL should not be applied to such patients.
However, while detecting and treating anemia in low risk outpatient surgical patients might be beneficial in the long term, it is of little to no benefit in the short term (2). These patients likely have a prevalence of anemia similar to that of the general population. Testing them for anemia is screening, not case-finding, and the approach must be different; screening should accord with the recommendations of authoritative groups who have carefully studied the issue (3–6). The most inclusive combination of these recommendations would lead to screening infants, menstruating adolescents, and pregnant females.
Although Hb tests are inexpensive, investigating the positives (most of which will turn out to be of limited consequence) generated from screening all healthy adults, is quite expensive and inconvenient, and it delays surgery. Investigation of all patients with Hb of 10 g/dL should be the responsibility of whoever orders the test. Such follow-up is best done in the primary-care clinical context, where repeated observation is allowed. The perioperative team has generally been ill-equipped and is poorly motivated to do such follow-up. Using the perioperative period for general medical screening exposes the patient to false assurance that all is well and perioperative physicians to litigation if anything can be remotely connected to the mild abnormality.
On the other hand, it is difficult to decide which patients can be safely excluded. To better define a threshold, we analyzed this same study population, looking for the presence or absence of any clinical indicator of potential anemia. If, instead of excluding all ASA I-II outpatient surgery patients from Hb testing, we excluded only those with no indicators of potential anemia at the preoperative examination, the risk of missing significant anemia was even lower. The prevalence of Hb < 9 in this excluded group would have been only 0.1%, and the absence of clinical indicators of anemia would have had a negative predictive value of 99.9%. This indicates that an easily identifiable group of low-risk patients (those with no clinical indicators of potential anemia) can be safely excluded from Hb testing. All others should be tested.
In an increasingly fragmented health care system, the clinical path described by Shander et al. is an exciting example of reintegration of primary and perioperative care. We will watch this with great interest. However, in such cooperative projects it will be important to keep clear that, for healthy low-risk surgical candidates, Hb testing is primary care screening, not perioperative medicine. It should be approached as such.
Ronald P. Olson
Preoperative Screening Unit
Duke University Medical Center
David Lubarsky, MD, MBA
Emanuel M. Papper Professor and Chair Department of Anesthesiology, Perioperative Medicine and Pain Management University of Miami/Jackson Memorial Hospital Miami, FL
1. Shander A, Javidroozi M, Goodnough, LT. Anemia screening in elective surgery: definition, significance and patients' interests. Anesth Analg 2006;103:778–9.
2. Olson RP, Stone A, Lubarsky D. The prevalence and significance of low preoperative hemoglobin in ASA 1 or 2 outpatient surgery candidates. Anesth Analg 2005;101:1337–40.
3. United States Preventive Services Task Force. Guide to clinical preventive services, 2nd ed. Chapter 22, Screening for iron deficiency anemia-including iron prophylaxis. Baltimore: Williams & Wilkins, 1996:231–46.
4. Centers for Disease Control and Prevention. Recommendations to prevent and control iron deficiency in the United States. MMWR 1998;47(No. RR-3):1–29.
5. American Academy of Family Physicians (AAFP). Summary of recommendations for clinical preventive services. Revision 6.0. Leawood, KS: American Academy of Family Physicians (AAFP), 2005.
6. Institute of Medicine. Iron deficiency anemia: recommended guidelines for the prevention, detection, and management among U.S. children and women of childbearing age. Washington, DC: National Academy Press, 1993.