Evaluating the role of faecal calprotectin in older adults: a retrospective observational study

Faecal calprotectin (FC) is a marker of gastrointestinal (GI) inflammation that is widely used in primary care to identify patients who need to be referred for endoscopic assessment. Most guidelines advise against its use in older adults because of higher rates of colorectal cancer (CRC) in this group, and many studies include only younger adults, even though FC is still used in older adults.

To evaluate FC performance in identifying inflammatory bowel disease (IBD) and significant organic pathology in adults aged ≥50 years, to help inform its use and interpretation in primary care. Where available, faecal immunochemical test (FIT) data were also analysed.

A retrospective observational study of patients who were referred from primary care to secondary care for colonoscopy at Imperial College Healthcare NHS Trust.

Patients who had undergone FC testing, followed by a colonoscopy, were recruited and grouped into younger adults (aged 18-49 years) and older adults (aged ≥50 years). Data were then collected using electronic health records to allow for analysis of FC diagnostic performance.

In total, 669 patients were included: 423 aged 18-49 years and 246 aged ≥50 years. There were no significant differences in FC levels between the groups (median FC level: 71 µg/g versus 85.5 µg/g respectively, P = 0.29). An FC level of >50 µg/g showed a high sensitivity for inflammatory bowel disease (IBD) in both groups (94.1% in those aged 18-49 years and 93.8% in those aged ≥50 years), but the positive predictive value was low - particularly in those aged ≥50 years (12.8%) versus the younger cohort (20.9%). An FC level of >50 µg/g outperformed FIT (threshold 10 µg/g) for the diagnosis of IBD and organic pathology in both groups. However, in patients aged ≥50 years, FIT outperformed FC at 150 µg/g for the diagnosis of organic pathology, including CRC.

These data show that FC remains a sensitive test in older adults. FC may have a role as a 'rule-out' test in adults aged ≥50 years who have lower GI symptoms and a negative FIT, when CRC is not suspected.