Longitude studies disease in motion. Faecal calprotectin, measured in stool, and C-reactive protein, measured in blood, provide different views of inflammation. Following them over months and years can reveal improvement, recurrence or persistent activity that is difficult to understand from an isolated result.
What we have shown
In 918 people with Crohn’s disease, higher calprotectin was associated with subsequent disease progression, hospitalisation or surgery, independently of symptoms and disease location. A later Edinburgh study found that reaching a calprotectin level below 250 µg/g within a year of diagnosis was associated with a lower risk of progression. These were observational findings, rather than trials proving that a particular monitoring strategy prevents complications.
Our large-scale trajectory analysis identified eight calprotectin patterns and eight CRP patterns in Lothian, with similar patterns in Danish cohorts. They included rapid remitters, delayed remitters, relapsing courses and persistent inflammation. The two biomarkers often placed the same person in different groups, showing why they should not be treated as interchangeable accounts of disease.
Current questions
We are investigating how inflammation accumulates over a lifetime, including its relationship with health beyond the bowel. Current questions include the consequences of spending longer outside treatment targets and what the earliest years of ulcerative colitis can tell us about later disease course.
The team’s open-source landmaRk software supports dynamic risk prediction using longitudinal models, including latent-class models. This methodological work asks how risk estimates can use new information while acknowledging differences between patients and uncertainty in the data.
Why it matters
The aim is to help patients and clinicians interpret the course of disease, recognise meaningful change earlier and make decisions that draw on the full history of someone’s IBD.