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Purpose: Nearly half the cases of thyroid cancer, a malignancy rapidly rising in incidence within the United States, are attributable to small and asymptomatic papillary thyroid cancers that will not increase mortality. A primary driver of thyroid cancer overdiagnosis is ultrasound use. It is therefore valuable to understand how inappropriate use of thyroid ultrasound is defined, analyze the current evidence for its frequency, and identify interventions to lessen misuse. Methods: Ovid MEDLINE(R), Ovid EMBASE, and Scopus databases were searched from inception to June 2020 for studies assessing inappropriate use of thyroid ultrasound. Reviewers, working independently and in duplicate, evaluated studies for inclusion, extracted data, and graded risk of bias. We used a random-effects model with a generalized linear mixed approach to calculate the mean overall proportion estimates of inappropriate use. Results: Seven studies (total n = 1573) met the inclusion criteria with moderate to high risk of bias. Inappropriate thyroid ultrasound use was described variably, using published practice guidelines, third-party expert reviewers, or author interpretations of the literature. The overall frequency of inappropriate thyroid ultrasound use was 46% (95% CI 15–82%; n = 388) and 34% (95% CI 16–57%; n = 190) among studies using guideline based definitions. The pooled frequency of iUS due to thyroid dysfunction (either hypothyroidism or thyrotoxicosis) was 17% (95% CI 7–37%; n = 191) and the frequency of iUS due to nonspecific symptoms without a palpable mass was 11% (95% CI 5–22%; n = 124). No study examined interventions to address inappropriate use. Conclusions: Low quality evidence suggests that inappropriate use of thyroid ultrasound is common. Interventional studies aiming to decrease the inappropriate use of thyroid ultrasound are urgently needed. [ABSTRACT FROM AUTHOR]

Clostridium difficile infection (CDI) is a leading cause of healthcare-associated infections, accounting for significant disease burden and mortality. The clinical spectrum of C. difficile ranges from asymptomatic colonization to toxic megacolon and fulminant colitis. CDI is characterized by new onset of ≥ 3 unformed stools in 24 h and is confirmed by laboratory test for the presence of toxigenic C. difficile. Currently, laboratory tests to diagnose CDI include toxigenic culture, glutamate dehydrogenase (GDH), nucleic acid amplification test (NAAT), and toxins A/B enzyme immunoassay (EIA). The sensitivities of these tests are variable with toxin EIA ranging from 53 to 60% and with NAAT at about 95%. Overall, the specificity is > 90% for these methods. However, the positive predictive value (PPV) depends on the disease prevalence with lower CDI rates associated with lower PPVs. Notably, the widespread use of the highly sensitive NAAT and its relatively lower clinical specificity have led to overdiagnosis of C. difficile by identifying carriers when NAAT is used as the sole diagnostic method. Overdiagnosis of C. difficile has resulted in unwarranted treatment, possibly attributing to resistance to metronidazole and vancomycin, increased risk for overgrowth of vancomycin-resistant enterococci strains in stool specimens, and increased hospitalization thereby impacting patient safety and healthcare costs. Strategies to optimize the clinical sensitivity and specificity of current laboratory tests are critical to differentiate the clinical CDI from colonization. To achieve high diagnostic yield, if preagreed institutional criteria for stool submission are not used, a multistep approach to CDI diagnosis is recommended, such as either GDH or NAAT followed by toxins A/B EIA in conjunction with laboratory stewardship by evaluating C. difficile test orders for appropriateness and providing feedback. Furthermore, antimicrobial stewardship, along with provider education on appropriate testing for C. difficile, is vital to differentiate CDI from colonization. [ABSTRACT FROM AUTHOR]