Existing research suggests that unexplained weight loss is a "low-risk, but not no-risk" symptom of cancer and serious disease in General Practice, for example between 1 in 200 and 1 in 30 patients with unexplained weight loss go on to develop cancer. However, it is not clear how GPs should investigate unexpected weight loss. Without clarification, GPs may wait too long before referring (choosing to watch and wait and potentially missing a diagnosis) or not long enough (overburdening hospital services and exposing patients to the risks of investigation).
This study involves an analysis of patients with unexpected weight loss to examine the extent to which weight loss indicates cancer or another serious disease in patients visiting to their GP. As weight is not routinely measured by GPs in the UK, we will first describe why and when GPs measure and record weight in their patient's electronic record. Secondly, patients will be entered into a cohort analysis - patients with and without weight loss codes in their electronic record will be followed up in the database to examine the number that turn out to have cancer or another serious disease within 24 months of reporting the weight loss.
The overall aim is to provide the evidence necessary to allow GPs to more effectively manage patients with unexplained weight loss.
Review of the existing evidence exposes key evidence gaps where questions remain unanswered:
1) How often and when is weight measured, and the symptom of unexpected weight loss coded, in NHS primary care?
2) What is the diagnostic predictive value of recorded weight loss, volunteered or elicited as a symptom, for cancer and serious disease in primary care?
A cohort analysis of UK Clinical Practice Research Datalink (CPRD) data to: 1) Describe how often the symptom of reported weight loss is recorded, and when weight is measured in NHS primary care; 2) Identify the predictive value of recorded weight loss for cancer and serious disease in primary care. The cohort analysis will compare the incidence of cancer over time in those with and without weight loss, using Cox regression to explore and adjust for covariates as appropriate. Preliminary work in CPRD estimates that weight loss as a symptom is recorded for about 52,500 patients >40 years, providing adequate statistical power and precision in relation to cancer overall and common cancers individually.
Health Outcomes to be Measured:
Outcome 1 - Objective weight measurement. Outcome 2 - Weight loss code.
NCRAS Cancer Registration Data;ONS Death Registration Data;Patient Level Index of Multiple Deprivation;Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation