CONVERSION FACTOR FOR PREDICTING ADENOMA DETECTION RATE FROM POLYP DETECTION RATE VARY ACCORDING TO COLONOSCOPY INDICATION AND GENDER OF ENDOSCOPED INDIVIDUALS

Aims:

Adenoma detection rate (ADR) is the primary quality indicator for colonoscopy; however, it is difficult to obtain in terms of time and personnel. Polyp detection rate (PDR) is an alternative indicator easily evaluated from administrative data. The main aim of the study was to assess whether PDR and ADR are correlated and to determine the conversion factor to predict ADR from PDR in preventive (screening and FOBT+) colonoscopies.

Methods:

The retrospective study included asymptomatic individuals aged 45 – 75 who underwent preventive colonoscopy in 2012 – 2015 as part of Czech multicentric study monitoring metabolic risk factors of colorectal cancer. Spearman's correlation coefficient was used to assess the relation between individual PDR and ADR. The resulting conversion factor to predict ADR from PDR was obtained by linear regression.

Results:

In total, the study included 1614 preventive colonoscopies performed by 16 endoscopists. The correlation between PDR and ADR in all preventive colonoscopies was high and statistically significant (Rs 0.82; p < 0.001). There is a stronger correlation between PDR and ADR in men (Rs 0.74; p = 0.002) and in screening colonoscopies (Rs 0.85; p < 0.001) (Figure 1). The conversion factor to convert ADR from PDR is 0.7185, 0.7582, and 0.6703 for all preventive, FOBT+ and screening colonoscopies respectively.

Conclusions:

There is a strong correlation between PDR and ADR; due to better accessibility, PDR may replace ADR in colonoscopy quality assessment. ADR may be estimated from PDR using a conversion factor that varies according to colonoscopy indication and gender of endoscoped individuals. With respect to the minimum ADR requested, i.e. 25% recommended by ASGE and ESGE identically, all preventive colonoscopies should reach PDR ≥35%.

Supported by grants MO1012 and Progres Q28/LF1.