Incidence of collagenous colitis in NHS Lothian: a population-based study.

Objective: Increases in incidence of collagenous colitis (CC) have been documented across Europe; however, previous data from NHS Lothian (1998-2003) demonstrated this to be a low-prevalence area. We aimed to assess incidence of CC in NHS Lothian over time by comparing a more recent cohort (2013-2018) with our existing cohort.

Methods: All histologically confirmed diagnoses of CC between 2013 and 2018 were obtained from the NHS Lothian colorectal pathology department (Western General Hospital, Edinburgh). Case record review was performed to obtain relevant demographic and clinical data. Data were also collected regarding the availability of colonoscopy in NHS Lothian.

Results: 224 cases of CC were diagnosed between 2013 and 2018, compared with 25 between 1998 and 2003. Mean annual incidence rose from 0.5/100 000 population to 4.3/100 000 population. Incidence in females ≥60 years old rose from 2.3/100 000 population to 22.4/100 000 population (p<0.001). The total number of colonoscopies performed increased by 179.1% from 15 262 (1998-2003) to 42 600 (2013-2018), with the number of CC cases per 1000 colonoscopies performed rising from 1.7 to 5.3 (p<0.001).

Conclusion: We describe the increasing incidence of CC in Southeast Scotland, with temporal trends comparable to other European countries. The increase is particularly marked in older females and parallels increasing numbers of colonoscopies being performed.