Tools for Practice Outils pour la pratique


#187 CBC (Confusing Broad Check) for Screening?


CLINICAL QUESTION
QUESTION CLINIQUE
What is the evidence for screening with a CBC (Complete Blood Count) in asymptomatic, non-pregnant adults?


BOTTOM LINE
RÉSULTAT FINAL
CBC or its components should NOT be ordered for screening asymptomatic non-pregnant adults as it does not reduce mortality. When CBC is tested routinely without cause, up to 11% are abnormal but <1% require management change. It is unclear which patients benefit and serious disease is virtually never found.  



CFPCLearn Logo

Reading Tools for Practice Article can earn you MainPro+ Credits

La lecture d'articles d'outils de pratique peut vous permettre de gagner des crédits MainPro+

Join Now S’inscrire maintenant

Already a CFPCLearn Member? Log in

Déjà abonné à CMFCApprendre? Ouvrir une session



EVIDENCE
DONNÉES PROBANTES
  • Systematic review of 16 Randomized Controlled Trials (RCTs) of periodic health checks (screening):1  
    • Four included CBC components with other screening tests and reported no cancer-specific or overall mortality reduction.   
  • CBC components in population screening, case-finding (looking for illness in higher risk people), hospital admission screening, and pre-op screening.   
    • Population screening: 
      • 1,080 non-pregnant women age 20-64, 11% anemic (hemoglobin <120g/L) but none had colon cancer.2 
    • Case-finding: 11 observational studies.  
      • Seven from 1987 review,3 evidence does not show benefit in identifying mild asymptomatic abnormalities. Example 
        • From 799 ambulatory patients 475 leukocyte tests, 11% abnormal but no asymptomatic disease identified.4   
      • Four other studies:  
        • 595 patients (1,540 CBC components ordered): 6.4% were abnormal, 1.2% investigated, 0.2% led to management change.5   
        • Others similar.6-8   
    • Pre-Op screening: From four observational studies (214-1,005 patients)9 management was changed 0%, 0%, 0.2% and 2%.   
    • Admission screening: Two observational studies (301-302 patients), ~11% had abnormal CBC components and ≤0.6% led to management changes.10,11   
  • Stating “management changed does not mean patients benefited.  
  • Harms of excess investigation not described.  
Context: 
  • Screening means testing healthy individuals for asymptomatic disease that could respond to early intervention to prevent suffering or mortality. 
  • When diseases are uncommon (~1%): Only ~16% of abnormals are real disease.12 
    • ~80% of abnormal leukocyte screenings were physiological or test variance.2   
    • 60% of abnormal CBC components normalized by 18 months.5  
  • Serious diseases like colon cancer have better screening tests (FIT testing).     
  • CDC, US Preventive Task Force, and Choosing Wisely do not recommend screening with CBC.13-15  
    • Only pregnancy screening consistently advised.13,14 
  • About 70% of primary care clinicians would order a screening CBC in a 55 year old woman16,17 and ordering CBC predicts other excess screening.16   


Latest Tools for Practice
Derniers outils pour la pratique

#367 Oral Calcitonin Gene-related Peptide Antagonists: A painfully long name for the acute treatment of migraines

What are the risks and benefits of ubrogepant for the acute treatment of episodic migraines?
Read Lire 0.25 credits available Crédits disponibles

#366 Looking for Closure: Managing simple excisions or wounds efficiently

What are some options for efficiency in wound closure?
Read Lire 0.25 credits available Crédits disponibles

#365 Shrooms for Glooms: Evidence for psilocybin for depression

What are the benefits and harms of psilocybin for treatment-resistant/recurrent depression?
Read Lire 0.25 credits available Crédits disponibles

This content is certified for MainPro+ Credits, log in to access

Ce contenu est certifié pour les crédits MainPro+, Ouvrir une session


Author(s)
Auteur(s)
  • G. Michael Allan MD CCFP
  • Jennifer Young MD CCFP-EM

1. Krogsbøll LT, Jørgensen KJ, Grønhøj Larsen C, et al. Cochrane Database Syst Rev. 2012; 10:CD009009.

2. Elwood PC, Waters WE, Greene WJ, et al. BMJ. 1967; 4:714-17.

3. Shapiro MF, Greenfield S. Ann Intern Med. 1987; 106:65-74.

4. Rich EC, Crowson TW, Connelly DP. JAMA. 1983: 249:633-6.

5. Rüttimann S, Clémençon D, Dubach UC. Ann Intern Med. 1992; 116(1):44-50.

6. Boland BJ, Wollan PC, Silverstein MD. Am J Med. 1996; 101(2):142-52.

7. Boland BJ, Wollan PC, Silverstein MD. Am J Med Sci. 1995; 309(4):194-200.

8. Domoto K, Ben R, Wei JY, et al. Am J Public Health. 1985; 75(3):243-5.

9. Czoski-Murray C, Lloyd Jones M, McCabe C, et al. Health Technol Assess. 2012; 16(50).

10. Frye EB, Hubbell FA, Akin BV, et al. J Gen Intern Med. 1987; 2(6):373-6.

11. Mozes B, Haimi-Cohen Y, Halkin H. Postgrad Med J. 1989; 65(766):525-7.

12. Wians FH. Lab Med. 2009; 40(2):105-13.

13. Centre for Disease Control and Prevention. Screening for Anemia 1998. Available at: https://wonder.cdc.gov/wonder/prevguid/p0000109/p0000109.asp#head033000000000000. Last accessed: March 14, 2017.

14. US Preventive Services Task Force. Available at: https://www.uspreventiveservicestaskforce.org/. Last accessed: March 14, 2017.

15. Choose Wisely Canada – Family Medicine. Available at: http://www.choosingwiselycanada.org/recommendations/family-medicine/. Last accessed: March 17, 2017.

16. Fung D, Schabort I, MacLean CA, et al. Can Fam Physician. 2015; 61(3):256-62.

17. Chacko KM, Feinberg LE. Am J Prev Med. 2007; 32(1):59-62.

Authors do not have any conflicts of interest to declare.

Les auteurs n’ont aucun conflit d’intérêts à déclarer.