Non–Contrast-Enhanced Computerized Tomography and Analgesic-Related Kidney Disease

Abstract

Previous studies suggested that the non-contrast-enhanced computerized tomography (CT) scan is a highly reliable tool for the diagnosis of analgesic-associated renal disease. However, this issue has not been addressed in the US population. A total of 221 incident patients with ESRD from different regions of the United States underwent a helical CT scan and detailed questioning about drug history. Specific renal anatomic criteria were developed to determine whether a constellation of CT findings (small indented calcified kidneys [SICK]) is linked to analgesic ingestion. For approximating use before the onset of renal disease, only analgesic ingestion at least 9 yr before starting dialysis was considered relevant. Fifteen patients met the criteria for SICK. This represented 7% of the enrolled patients and approximately 1% of the total ESRD population. There was a significant increase in the estimated risk among patients with a history of heavy aspirin ingestion (odds ratio [OR] 7.4 [95% confidence interval (CI) 1.2 to 43] for >1 kg lifetime; OR 8.8 [95% CI 1.2 to 66] for >0.3 kg/yr). Total analgesic ingestion of >0.3 kg/yr also was significantly associated with SICK (OR 8.2; 95% CI 1.5 to 45). These findings were accounted for largely by combination products that contained aspirin and phenacetin (used by three patients with SICK), which are no longer available. In addition, the CT finding of SICK was present only in a minority of heavy analgesic users, yielding a sensitivity of 5 to 26%. Findings of SICK are infrequent in the US ESRD population and do not occur among a sufficient proportion of heavy analgesic users to render the non-contrast-enhanced CT scan a sensitive tool to detect analgesic-associated kidney injury.

Over-the-Counter Analgesic Use

“…4 It turns out that in comparison with previous studies, the sensitivity of the noncontrast CT scan for the detection of analgesic-associated kidney injury was too low to be used as a routine test; that is, a specificity of Ͼ95%, comparable with the earlier reports, was found. The low prevalence of AN (clearly Ͻ5%) found in the United States, however, precluded calculating the clinically relevant sensitivity of the test.…”

“…Finally, it is well established that patients with AN used analgesics on a daily basis and at least for a period of 5 yr, resulting in a total analgesic consumption of at least 1500 U. 4,8 As shown in Figure 2, several studies suffered from dosage bias because they used a total amount that was far below the minimum consumption described in patients with AN. 13,19,20 The epidemiologic literature concerning the role of different substances that cause AN is limited and controversial.…”

What do we know about chronic renal failure in young adults? I. Primary renal disease

“…Computed tomography and magnetic resonance imaging should give useful information, but there is very little published on renal imaging in uraemia, with the exception of analgesic nephropathy [32,33]. It is difficult to obtain accurate information on the shape of small contracted kidneys.…”

Analgesic Nephropathy and Renal Replacement Therapy in Australia

“…Diagnoses reported by the individual units were not routinely confirmed by requests for radiologic or other investigations that may have been performed. Despite interests in using computed tomography to diagnose classical AN (17,18), diagnosis is still often by drug history supported by radiologic signs (papillary calcification or necrosis), which by themselves are nonspecific. Cases of nonsteroidal anti-inflammatory drugs contributing to endstage kidney disease could also have been labeled as AN, despite their differences; however, there were high levels of awareness of AN among Australian nephrologists throughout the study period.…”