Introduction Contrast induced nephropathy (CIN) is the third most common cause of hospital-acquired acute kidney injury 1 and is associated with increased incidence of requiring dialysis, and with increased mortality. This is particularly the case in those with pre-existing renal impairment or other co-morbidities, such as diabetes or heart failure. Computed tomography of the chest with IV contrast is now an integral part in the diagnosis and staging of patients with lung cancer. In an effort to reduce time to diagnosis, contrast studies are routinely performed early, often prior to first review in secondary care. As a result, this population may have inadequate assessment of CIN risk. To investigate this further we carried out a retrospective analysis of the monitoring of the renal function of patients with lung cancer who underwent a CT chest with contrast at a London teaching hospital.
Methods A consecutive series of 100 patients diagnosed between November 2011 and January 2012 was identified using the local lung cancer registry. We examined how frequently renal function was monitored in relation to the patients’ CT chest scans. Whether this was clinically adequate was decided with reference to recommendations from the Royal College of Radiologists.
Results Of 30 CKD patients, 14 (47%) had appropriate pre-contrast bloods. Of patients identified as having diabetes (n=10), 50% had appropriate pre-contrast bloods.
Of 29 patients admitted acutely, 28 (97%) had appropriate pre-contrast bloods.
Of the 37 remaining patients, outpatients with normal renal function, 26 (70%) had appropriate pre-contrast bloods.
Conclusions This study demonstrated that almost all inpatients undergoing CT chest with IV contrast had appropriate monitoring of their renal function. However, this was true of a significantly lower proportion of outpatients. Perhaps of most concern was that approximately half of those patients at the highest risk of developing contrast-induced nephropathy were monitored appropriately. We suggest that earlier CT scanning, in the interests of expediting diagnosis and treatment, could be exposing more patients to increased risk of harm associated with administration of IV contrast.
Hou SH et al. Hospital-acquired renal insufficiency: a prospective study. Am J Med. 1983; 74243–8.