Individual inflammatory marker abnormalities or inflammatory marker scores to identify primary care patients with unexpected weight loss for cancer investigation?

Abstract

Background Combinations of inflammatory markers are used as prognostic scores in cancer patients with cachexia. We investigated whether they could also be used to prioritise patients attending primary care with unexpected weight loss for cancer investigation. Methods We used English primary care electronic health records data linked to cancer registry data from 12,024 patients with coded unexpected weight loss. For each individual inflammatory marker and score we estimated the sensitivity, specificity, likelihood ratios, positive predictive value (PPV) and the area under the curve along with 95% confidence intervals for a cancer diagnosis within six months. Results The risk of cancer associated with two abnormal inflammatory markers combined in a score was higher than the risk associated with individual inflammatory marker abnormalities. However, the risk of cancer in weight loss associated with individual abnormalities, notably a raised C-reactive protein, was sufficient to trigger further investigation for cancer under current NICE guidelines. Conclusions If scores including pairs of inflammatory marker abnormalities were to be used, in preference to individual abnormalities, fewer people would be investigated to diagnose one cancer with fewer false positives, but fewer people with cancer would be diagnosed overall.

Measured weight loss as a precursor to cancer diagnosis: retrospective cohort analysis of 43 302 primary care patients

“…14,15 As most patients presenting to primary care with UWL will not have cancer, diagnostic strategies that avoid the harms of unnecessary invasive and costly investigation are required. 13,[16][17][18][19] The amount of weight loss and the period of time over which it occurs that is most strongly associated with underlying cancer remains poorly defined. 12,15,20 Almost all studies in this area are retrospective observational studies that define weight loss by means of diagnostic codes entered into the electronic health record (EHR).…”

“… 14 , 15 As most patients presenting to primary care with UWL will not have cancer, diagnostic strategies that avoid the harms of unnecessary invasive and costly investigation are required. 13 , 16 , 17 , 18 , 19 …”

“…UWL may go undetected or may be misattributed due to diurnal fluctuations in weight, expected weight changes with age, diet or exercise, obesity, and variation in weight measurement frequency 14,15 . As most patients presenting to primary care with UWL will not have cancer, diagnostic strategies that avoid the harms of unnecessary invasive and costly investigation are required 13,16–19 …”

Combining simple blood tests to identify primary care patients with unexpected weight loss for cancer investigation: Clinical risk score development, internal validation, and net benefit analysis

“…Our previous work has shown that the presence of individual co-occurring clinical features increases the likelihood of cancer sufficiently to rule-in cancer investigation [ 5 ]. However, the absence of individual co-occurring clinical features, including pairs of normal inflammatory markers, do not reduce the likelihood of cancer sufficiently enough to rule-out patients from further cancer investigations [ 5 , 6 ]. Primary care clinicians commonly request multiple blood tests when patients present with UWL [ 5 , 7 ].…”

“…Primary care clinicians commonly request multiple blood tests when patients present with UWL [ 5 , 7 ]. There is little guidance on how clinicians should interpret these blood tests in combination or which are most relevant for use in clinical practice [ 1 , 6 ]. When baseline investigations are normal, a watchful waiting approach may be preferable to invasive testing [ 8 ].…”