Chiefs’ Inquiry Corner – 4/11/22

April 12, 2022

Chief residents of the NYU Langone Internal Medicine Residency give quick-and-easy, evidence-based answers to interesting questions posed by house staff, both in their clinics and on the wards.

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 The STOP-Bang questionnaire was first developed in 2008 to screen for obstructive sleep apnea in people who were undergoing presurgical evaluations. It consists of four subjective items (yes/no answers): Snoring, Tiredness, Observed apnea, history of high blood Pressure) and four demographics items (BMI, Age, Neck circumference, Gender). A score of 3 or greater indicates a high risk of obstructive sleep apnea, warranting further evaluation and testing. The questionnaire has been studied in different patient populations (including sleep clinic patients and surgical populations) but demonstrates a consistently high sensitivity (for example, 94% sensitivity in detecting moderate-to-severe OSA in sleep clinic patients, and 91% sensitivity in detecting moderate-to-severe OSA in surgical patients). As STOP-Bang score increases, the probability of moderate and severe OSA increases.  Of note, the specificity is much less (low 30%s for both surgical and sleep clinic populations), but given its brevity and ease of administration, it is still a good screening tool for a condition such as OSA that remains underdiagnosed but is associated with a number of serious sequelae, including cardiovascular disease, cerebrovascular disease, metabolic disorders, and impaired neurocognitive function.

References: Validation of the STOP-Bang Questionnaire as a Screening Tool for Obstructive Sleep Apnea among Different Populations: A Systematic Review and Meta-Analysis
 Nonalcoholic fatty liver disease (NAFLD), the hepatic manifestation of metabolic syndrome, is the leading cause of liver disease worldwide. Generally, weight loss is the primary therapy for most patients with NAFLD who are overweight (BMI >25 kg/m2) or obese (BMI >30 kg/m2), and can lead to improvement in liver biochemical tests, liver histology, serum insulin levels, and quality of life. However, bariatric surgery can be a promising approach for obese patients with NAFLD who do not meet their weight loss goals after six months of lifestyle interventions. In the recently published SPLENDOR study of 1158 patients with histologically confirmed NASH and obesity, bariatric surgery (gastric bypass or sleeve gastrectomy) was associated with a lower 10 year cumulative incidence of major adverse liver outcomes (2.3 versus 9.6 percent) and major cardiovascular events (8.5 versus 15.7 percent) compared with nonsurgical management. Major adverse liver outcomes was defined as a composite end point of progression to histologic cirrhosis, clinical (decompensated) cirrhosis, development of hepatocellular carcinoma, liver transplant, or liver-related mortality. The results suggest that for patients with appropriate indications for bariatric surgery (BMI ≥40 or ≥35 with obesity-related conditions) and NASH with fibrosis, clinicians should consider referral for bariatric surgery. Note that following bariatric surgery, patients should continue to have liver function tests monitored given the potential for worsening liver fibrosis in some patients.

References: Association of Bariatric Surgery With Major Adverse Liver and Cardiovascular Outcomes in Patients With Biopsy-Proven Nonalcoholic Steatohepatitis
The presence of cirrhosis as a risk factor for Vibrio vulnificus infection is a commonly tested association on board exams, but how does this medical condition actually increase vulnerability to this particular infection? Vibrio vulnificus is a gram-negative rod ubiquitous in coastal water; with a case-fatality rate of >50%, it is the leading cause of seafood-related deaths in the United States. While wound infections (from exposure to so-called ‘brackish water’) have occurred in people without significant medical history (usually leading to a mild cellulitis), sepsis secondary to V. vulnificus infection (with major risk factor for exposure being the ingestion of raw or undercooked shellfish, particularly raw oysters) occurs almost exclusively in people with immunosuppression, particularly those with chronic liver disease (including cirrhosis, EtOH-related liver disease, and/or chronic infection with Hepatitis B and/or C). People with cirrhosis often have immune system dysfunction and dysregulation, decreased complement levels, and diminished cellular phagocytic and chemotactic capabilities, all of which limit their ability to defend against the virulent Vibro. Additionally, in the presence of portal hypertension, V. vulnificus may bypass the hepatic reticuloendothelial system and directly enter the portal system. The elevated iron levels frequently found in chronic liver disease (particularly hemochromatosis) also foster V. vulnificus growth. The extracellular toxins produced by V. vulnificus destroy tissue and basement membranes in blood vessels, leading to the hemorrhagic and edematous skin changes (including bullae) frequently seen in people with disseminated infection. High index of suspicion should be maintained in people with severe skin lesions, sepsis, and cirrhosis or other forms of chronic liver disease, as the treatment of choice, doxycycline in conjunction with a third-generation cephalosporin such as ceftazidime, is not often part of empiric antibiotic therapy for sepsis and/or severe cellulitis. Even with timely administration of antibiotics (within <24h), mortality rates may approach 33%, with one case series reporting 100% mortality when proper antibiotic administration was delayed by more than 72h after illness onset. 

References: Vibrio vulnificus oysters: pearls and perils