Item analysis: the impact of distractor efficiency on the difficulty index and discrimination power of multiple-choice items.

BACKGROUND: Distractor efficiency (DE) of multiple-choice questions (MCQs) responses is a component of the psychometric analysis used by the examiners to evaluate the distractors' credibility and functionality. This study was conducted to evaluate the impact of the DE on the difficulty and discrimination indices. METHODS: This cross-sectional study was conducted from April to June 2023. It utilizes the final exam of the Principles of Diseases Course with 45 s-year students. The exam consisted of 60 type A MCQs. Item analysis (IA) was generated to evaluate KR20, difficulty index (DIF), discrimination index (DIS), and distractor efficiency (DE). DIF was calculated as the percentage of examinees who scored the item correctly. DIS is an item's ability to discriminate between higher and lower 27% of examinees. For DE, any distractor selected by less than 5% is considered nonfunctional, and items were classified according to the non-functional distractors. The correlation and significance of variance between DIF, DI, and DE were evaluated. RESULTS: The total number of examinees was 45. The KR-20 of the exam was 0.91. The mean (M), and standard deviation (SD) of the DIF of the exam was 37.5(19.1), and the majority (69.5%) were of acceptable difficulty. The M (SD) of the DIS was 0.46 (0.22), which is excellent. Most items were excellent in discrimination (69.5%), only two were not discriminating (13.6%), and the rest were of acceptable power (16.9%). Items with excellent and good efficiency represent 37.3% each, while only 3.4% were of poor efficiency. The correlation between DE and DIF (p = 0.000, r= -0.548) indicates that items with efficient distractors (low number of NFD) are associated with those having a low difficulty index (difficult items) and vice versa. The correlation between DE and DIS is significantly negative (P = 0.0476, r=-0.259). In such a correlation, items with efficient distractors are associated with low-discriminating items. CONCLUSIONS: There is a significant moderate negative correlation between DE and DIF (P = 0.00, r = -0.548) and a significant weak negative correlation between DE and DIS (P = 0.0476, r = -0.259). DIF has a non-significant negative correlation with DIS (P = 0.7124, r = -0.0492). DE impacts both DIF and DIS. Items with efficient distractors (low number of NFD) are associated with those having a low difficulty index (difficult items) and discriminating items. Improving the quality of DE will decrease the number of NFDs and result in items with acceptable levels of difficulty index and discrimination power.

Molecular Epidemiology of Carbapenem-Resistant K. pneumoniae Clinical Isolates from the Adult Patients with Comorbidities in a Tertiary Hospital, Southern Saudi Arabia.

Hospitalized patients are likely to have chronic illnesses and are at an increased risk of mortality due to infection caused by MDR bacteria. We aimed to identify carbapenem-resistant genes carrying Klebsiella pneumoniae (K. pneumoniae) isolates and their risk factors recovered from adult patients with comorbidities. A cross-sectional study was carried out between April 2021 and December 2021 at King Abdullah Hospital (KAH) in Bisha province, Saudi Arabia. Seventy-one multi-drug resistant K. pneumoniae recovered from clinical samples and screened for carbapenemase genes of blaOXA-48-like, blaNDM-1, blaKPC, blaVIM, and blaIMP. Of 71 MDR K. pneumoniae examined, 47 (66.2%) isolates harbored various carbapenemase genes. The most prevalent single resistance gene was blaOXA-48-like (62.5%; n = 25), and 33.3% of them were recovered from sputum isolates. The blaNDM-1 gene was detected in 12 (30.0%) isolates, and eight of them were recovered from urine (n = 4) and blood (n = 4). Two (5.0%) single blaKPC genes were recovered from the sputum (n = 1) and blood (n = 1) isolates. In contrast, no blaIMP- and blaVIM-carrying isolates were detected. The co-existence of two resistance genes between blaOXA-48-like and blaNDM-1 was found in six strains, whereas only one strain was found to be produced in the three genes of blaNDM-1, blaKPC, and blaOXA-48-like. There were statistically significant associations between the presence of carbapenem-gene-carrying K. pneumoniae and patients' gender (χ2(1) = 5.94, p = 0.015), intensive care unit admission (χ2(1) = 7.649, p = 0.002), and chronic obstructive pulmonary disease (χ2(1) = 4.851, p = 0.028). The study highlighted the existence of carbapenemase-producing K. pneumoniae, particularly blaOXA-48-like and blaNDM-1, in patients with comorbidities. Our findings emphasize the importance of the molecular characterization of resistance-determinant-carrying bacterial pathogens as a part of infection control and prevention in hospital settings.