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Effect of Annual Colonoscopy Volume and Years in Practice on Polyp Detection and Removal

      To the Editor:
      I read with great interest the article by Ko et al
      • Ko C.W.
      • Dominitz J.A.
      • Green P.
      • Kreuter W.
      • Baldwin L.M.
      Specialty differences in polyp detection, removal, and biopsy during colonoscopy.
      published in a recent issue of The American Journal of Medicine. The authors are certainly to be commended for highlighting significant predictors of polyp detection, polyp removal, and diagnostic biopsy, which have important implications for the effectiveness of colonoscopy.
      The authors conclude that their findings suggest that very low colonoscopy volumes may be associated with suboptimal detection of colorectal pathology.
      • Ko C.W.
      • Dominitz J.A.
      • Green P.
      • Kreuter W.
      • Baldwin L.M.
      Specialty differences in polyp detection, removal, and biopsy during colonoscopy.
      However, polyp detection and removal results also were similar (and suboptimal) for very high-volume providers. The authors report a complex relationship between annual colonoscopy volume and their outcome measures, with overall polyp detection and removal significantly more likely for moderate-volume providers compared with very high- or low-volume providers.
      • Ko C.W.
      • Dominitz J.A.
      • Green P.
      • Kreuter W.
      • Baldwin L.M.
      Specialty differences in polyp detection, removal, and biopsy during colonoscopy.
      One possibility, as stated by the authors, is shorter withdrawal time for high-volume providers, leading to a lower likelihood of polyp detection.
      • Ko C.W.
      • Dominitz J.A.
      • Green P.
      • Kreuter W.
      • Baldwin L.M.
      Specialty differences in polyp detection, removal, and biopsy during colonoscopy.
      The authors found that gastroenterologists had the highest median annual colonoscopy volume, and yet, had significantly higher polyp detection and removal rates compared with the nongastroenterologists.
      • Ko C.W.
      • Dominitz J.A.
      • Green P.
      • Kreuter W.
      • Baldwin L.M.
      Specialty differences in polyp detection, removal, and biopsy during colonoscopy.
      This is contrary to their finding that highest-volume providers had lower polyp detection and removal rates compared with moderate-volume providers. Even other studies have found no correlation between incidence of interval colorectal cancer after negative colonoscopy and annual colonoscopy volume.
      • Singh H.
      • Nugent Z.
      • Mahmud S.M.
      • Demers A.A.
      • Bernstein C.N.
      Predictors of colorectal cancer after negative colonoscopy: a population-based study.
      • Rabeneck L.
      • Paszat L.F.
      • Saskin R.
      Endoscopist specialty is associated with incident colorectal cancer after a negative colonoscopy.
      However, these studies also found nongastroenterologists to have a higher risk of interval colorectal cancer after negative colonoscopy.
      • Singh H.
      • Nugent Z.
      • Mahmud S.M.
      • Demers A.A.
      • Bernstein C.N.
      Predictors of colorectal cancer after negative colonoscopy: a population-based study.
      • Rabeneck L.
      • Paszat L.F.
      • Saskin R.
      Endoscopist specialty is associated with incident colorectal cancer after a negative colonoscopy.
      It would be interesting to study the affect of colonoscopy volume for each specialty separately.
      Another surprising observation was that the likelihood of polyp detection and removal was inversely related to physician years in practice.
      • Ko C.W.
      • Dominitz J.A.
      • Green P.
      • Kreuter W.
      • Baldwin L.M.
      Specialty differences in polyp detection, removal, and biopsy during colonoscopy.
      One would expect a higher rate of polyp detection and removal with increasing years of experience in performing colonoscopy. As the authors suggested, it might be possible that more experienced colonoscopists would be more experienced in identifying hyperplastic polyps and not removing them, accounting for a lower polyp removal rate.
      • Ko C.W.
      • Dominitz J.A.
      • Green P.
      • Kreuter W.
      • Baldwin L.M.
      Specialty differences in polyp detection, removal, and biopsy during colonoscopy.
      Although this could affect the polyp removal rate, this should not affect the polyp detection rate or the adenoma detection rate (ADR). Kaminski et al
      • Kaminski M.F.
      • Regula J.
      • Kraszewska E.
      • et al.
      Quality indicators for colonoscopy and the risk of interval cancer.
      also found a similar relation between ADR and colonoscopic experience. Compared with colonoscopists with more than 10 years of experience, colonoscopists with less than 5 years of experience were significantly more likely to have ADR ≥15% (23% vs 47%, respectively; P=.006), and less likely to have ADR <15% (77% vs 52%, respectively; P=.006) and ADR <11% (53% vs 30%, respectively; P=.02).
      • Kaminski M.F.
      • Regula J.
      • Kraszewska E.
      • et al.
      Quality indicators for colonoscopy and the risk of interval cancer.
      The reasons for these unexpected but consistent findings across different studies are unclear. Further studies are needed to better understand these factors and complex interplay between them, and to identify the mechanisms for these differences.

      References

        • Ko C.W.
        • Dominitz J.A.
        • Green P.
        • Kreuter W.
        • Baldwin L.M.
        Specialty differences in polyp detection, removal, and biopsy during colonoscopy.
        Am J Med. 2010; 123: 528-535
        • Singh H.
        • Nugent Z.
        • Mahmud S.M.
        • Demers A.A.
        • Bernstein C.N.
        Predictors of colorectal cancer after negative colonoscopy: a population-based study.
        Am J Gastroenterol. 2010; 105: 663-673
        • Rabeneck L.
        • Paszat L.F.
        • Saskin R.
        Endoscopist specialty is associated with incident colorectal cancer after a negative colonoscopy.
        Clin Gastroenterol Hepatol. 2010; 8: 275-279
        • Kaminski M.F.
        • Regula J.
        • Kraszewska E.
        • et al.
        Quality indicators for colonoscopy and the risk of interval cancer.
        N Engl J Med. 2010; 362: 1795-1803

      Linked Article

      • The Reply
        The American Journal of MedicineVol. 124Issue 2
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          We thank Rustagi for his interest in our article. The relationship among colonoscopy volume, specialty, and polyp detection rates is complex, and we have provided further data about the effect of colonoscopy volume separately for each specialty (Table 1). Because of the relatively small number of very high-volume endoscopists in the primary care or surgical specialties, we have combined some specialties in Table 1. These data show relationships among colonoscopy volume and polyp detection, polyp removal, and biopsy rates that are generally similar to those reported in our original article, particularly for gastroenterologists.
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