Screening tool accurately predicts Cushing’s syndrome in most at-risk patients
A scoring system based on clinical signs and a late-night salivary cortisol test accurately predicted Cushing’s syndrome in at-risk patients, with only one missed case, according to recent findings.
In a prospective, multicenter study, Antonio León-Justel, PhD, of the biochemistry department at the Hospital Universitario Virgen del Rocío in Seville, Spain, and colleagues analyzed data from 353 patients treated in endocrinology units in 13 university hospitals in Spain between 2012 and July 2013. All participants had at least two of five features compatible with Cushing’s syndrome, including obesity, hypertension, poorly controlled diabetes, hirsutism with menstrual disorders and osteoporosis; none of the included patients was referred to clinic with the suspicion of Cushing’s syndrome. All patients underwent late-night salivary cortisol and serum cortisol measurements after a low-dose (1 mg) dexamethasone test; those with discordant results were followed until December 2014 (mean follow-up time, 22.2 months).
Within the cohort, 26 (7.4%) patients were diagnosed with Cushing’s syndrome (20 adrenocorticotropic hormone-dependent; six of adrenal origin). In univariate logistic regression analysis, researchers found that muscular atrophy (OR = 15.2), followed by osteoporosis (OR = 4.6), dorsocervical fat pad (OR = 3.32), absence of obesity (OR = 0.21) and absence of type 2 diabetes (OR = 0.26), were associated with Cushing’s syndrome; late-night salivary cortisol values were also related (OR = 1.26). However, after multivariable adjustment, researchers found that muscular atrophy (OR = 9.04; 95% CI, 2.36-34.65), osteoporosis (OR = 3.62; 95% CI, 1.16-11.35) and dorsocervical fat (OR = 3.3; 95% CI, 1.52-7.17) remained as independent variables with Cushing’s syndrome.
“Obesity and type 2 diabetes displayed a negative association with [Cushing’s syndrome],” the researchers wrote. “These results might seem paradoxical a priori, but we want to stress that in our analyzed cohort, the prevalence of obesity and diabetes was exceedingly high (likely reflecting the reasons for referral to endocrinology units).”
In receiver operating characteristic (ROC) analysis, researchers determined that a cutoff value of 9.17 nmol/L for late-night salivary cortisol provided the best results, with an area under the curve of 0.893 (P < .001), a sensitivity of 88.5% and specificity of 83.2%.
Researchers developed a risk-scoring system, determining cutoff values from a ROC curve. The estimated area under the ROC curve was 0.93 (P < .001), with a sensitivity of 96.2% and specificity of 82.9%.
“Selecting this cutoff value of four, 271 of 327 subjects (83%) without [Cushing’s syndrome] were correctly identified, while only 1 of 26 [Cushing’s syndrome] cases was missed,” the researchers wrote. “Our model yielded 56 false positives.
“Although all the assessments were performed by specialists (endocrinologists) in our study, this scoring system could be easily tested in independent cohorts and different settings such as primary care or hypertension clinics,” the researchers wrote. “At the very least, our diagnostic prediction model could be used as a framework for future studies and potential improvements in diagnostic performance.” – by Regina Schaffer
Disclosure: Leon-Justel and another researcher report receiving a research grant from Novartis Oncology, Spain.