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PubMed2003

The STARD statement for reporting studies of diagnostic accuracy: explanation and elaboration.

The quality of reporting of studies of diagnostic accuracy is less than optimal. Complete and accurate reporting is necessary to enable readers to assess the potential for bias in the study and to evaluate the generalizability of the results. A group of scientists and editors has developed the STARD (Standards for Reporting of Diagnostic Accuracy) statement to improve the reporting the quality of reporting of studies of diagnostic accuracy. The statement consists of a checklist of 25 items and flow diagram that authors can use to ensure that all relevant information is present. This explanatory document aims to facilitate the use, understanding, and dissemination of the checklist. The document contains a clarification of the meaning, rationale, and optimal use of each item on the checklist, as well as a short summary of the available evidence on bias and applicability. The STARD statement, checklist, flowchart, and this explanation and elaboration document should be useful resources to improve reporting of diagnostic accuracy studies. Complete and informative reporting can only lead to better decisions in health care.

Algorithms↗
PubMed2003

Accuracy of computer diagnosis of melanoma: a quantitative meta-analysis.

BACKGROUND: Recent developments in computer technology have raised expectations that fully automated diagnostic instruments will become available to diagnose cutaneous melanoma without the need of human expertise. OBJECTIVES: To critically review the contemporary literature on computer diagnosis of melanoma, evaluate the accuracy of such computer diagnosis, analyze the influence of study characteristics, and compare the accuracy of computer diagnosis of melanoma with human diagnosis. METHODS: Quantitative meta-analysis of published reports. DATA SOURCES: Eligible studies were identified by a MEDLINE search covering the period from January 1991 to March 2002, by manual searches of the reference lists of retrieved articles, and by direct communication with experts. RESULTS: Thirty studies with substantial differences in methodological quality were deemed eligible for meta-analysis. Five of these complied with the predetermined list of "good quality" requirements, but none met all methodological quality requirements. Ten of these studies compared the performance of computer diagnosis with human diagnosis. The diagnostic accuracy achieved with computer diagnosis was statistically not different from that of human diagnosis (log odds ratios, 3.36 vs 3.51; P =.80). The diagnostic performance of the computer diagnosis was better for studies that used dermoscopic images than for studies that used clinical images (log odds ratios, 4.2 vs 3.4; P =.08). Other study characteristics did not significantly influence the accuracy of the computer diagnosis. CONCLUSIONS: The computer diagnosis of melanoma is accurate under experimental conditions, but the practical value of automated diagnostic instruments under real-world conditions is currently unknown. We suggest minimum requirements for methodological quality in future experimental studies or, ideally, randomized controlled trials.

Clinical Trials as Topic↗
PubMed1981

Accuracy of ultrasound intraocular lens calculation.

A review of the literature was made to evaluate the prediction accuracy of intraocular lens calculations. A uniform standard formula (percentage +/- 1.0 diopter/percentage +/- 2.0 D/range of error) for reporting accuracy was used to evaluate the accuracy of reports in the literature, as well as the accuracy of an ultrasound unit (Kretz 7100 MA), the HOffer formula, use of a standard 3.5-mm anterior chamber depth, and addition of a retinal thickness factor to the measured ultrasound axial length. The appropriateness of technicians performing this procedure also was evaluated. Results of previous studies show that the use of another ultrasound unit (Sonometrics DBR) and Binkhorst's formula is the least clinically accurate method.

Eye↗
PubMed2000

Accuracy of computer navigation in ear, nose, throat surgery: the influence of matching strategy.

OBJECTIVE: To measure the effect of 4 different matching strategies on the accuracy of computer navigation on the face and within the nose and rhinopharynx. DESIGN: Survey. SETTING: Laboratory study. SUBJECTS: Six human cadavers studied within 24 hours of death. INTERVENTIONS: A commercially available navigation system with infrared optical tracking was used for computer navigation on the face and within the nose of the subjects after matching with external fiducials or with 3 different configurations of anatomical landmarks. Navigation errors were measured and correlated to matching strategies and compared through statistical analysis. RESULTS: Matching with external fiducials on the face results in smaller navigation error than matching with anatomical landmarks. The configuration of matching strategies with anatomical landmarks also significantly determines the accuracy of computer navigation, especially when different locations of accuracy measurement are considered. CONCLUSION: Statistically significant findings have shown that the choice of a matching strategy is a major factor in the accuracy of computer navigation for ear, nose, throat surgery. Arch Otolaryngol Head Neck Surg. 2000;126:1462-1466

Cadaver↗
PubMed2004

The diagnostic accuracy of computed tomography in pediatric chronic rhinosinusitis.

OBJECTIVE: To determine the accuracy of computed tomography (CT) in the diagnosis of pediatric chronic rhinosinusitis (CRS). SETTING: Multi-institutional prospective dual cohort study. METHODS: Two cohorts of children undergoing CT of the paranasal sinuses were prospectively evaluated. The first cohort consisted of children undergoing CT in preparation for endoscopic sinus surgery (diseased group). The second cohort consisted of children undergoing CT for nonsinusitis reasons (nondiseased control group). Sinus CT scans were scored according to the Lund-MacKay system. Diagnostic accuracy was quantified with the receiver operating characteristic curve. Sensitivity, specificity, and predictive value analyses were conducted. RESULTS: A total of 66 pediatric patients (mean age, 8 years) were studied in the diseased group and exhibited a mean Lund score of 10.4 (95% confidence interval, 9.2-11.5); 192 control patients (mean age, 9 years) exhibited a mean Lund score of 2.8 (95% confidence interval, 2.4-3.2). The area under the curve for the receiver operating characteristic was 0.923 (P<.001), indicating excellent diagnostic accuracy. Adopting a Lund score cutoff of 5 to represent true disease, the CT scan demonstrated a sensitivity and specificity of 86% and 85%, respectively. Lund scores of 2 or less have an excellent negative predictive value, whereas Lund scores of 5 or greater have an excellent positive predictive value (ie, strongly indicate true disease). CONCLUSIONS: The sinus CT scan demonstrates excellent diagnostic accuracy for the diagnosis of pediatric CRS, with excellent sensitivity and specificity. However, its predictive value depends substantially on the base rate prevalence of CRS in the population being evaluated.

Case-Control Studies↗
PubMed1991

Improved speed and accuracy of calculations with a programmable calculator in pediatric emergency scenarios.

Both mathematical and selection errors may occur when ordering drug or fluid therapy in a busy emergency department. In an attempt to improve the speed and accuracy of such calculations, we programmed a hand-held calculator to assist in drug and intravenous fluid therapy dosages and rates for three emergency situations: diabetic ketoacidosis, asthma, and asystole. Performance by 58 subjects at various levels of training was compared when using either the programmable calculator or standard materials and methods. When standard methods were used, an average of 30.6 minutes was needed to complete the three scenarios, with an accuracy of 73%; by contrast, use of programmable calculator resulted in a significant decline in time needed to calculate doses (an average of only 8.5 minutes), with an improved accuracy of 98%. The use of a programmable calculator can result in a significant improvement in both speed and accuracy of drug and fluid selection and dosage and rate calculations, regardless of the level of the subject's medical training.

Age Factors↗
PubMed1975

Accuracy of ultrasound in diagnosing abdominal masses.

B-mode ultrasonography was performed in 246 patients with suspected abdominal masses over a seven-year period. In 105 (40 percent), the accuracy of ultrasonic diagnosis was evaluated surgically. Sonography was proven correct in 60 (57 percent) patients who had undergone operation. Among 141 patients who had not undergone operation and whose diagnoses were established by other means, ultrasonography agreed with the clinical diagnosis in 69 (31 percent). Ultrasound accuracy, as confirmed by operation, was highest for splenic masses (100 percent) and for aortic aneurysm (88 percent). Liver masses were correctly identified in 56 percent of patients and gallbladder lesions in 38 percent. While only a 48 percent accuracy was obtained in diagnosing pancreatic disease, 64 percent of all pseudocysts were localized. Ultrasonography correlated positively with operative findings in 56 percent of renal masses. Intraperitoneal abscess was accurately diagnosed in 61 percent of patients but retroperitoneal adenopathy in only 33 percent. Abdominal ultrasonography, while accurately diagnosing splenic and aortic masses, failed to identify approximately half of other mass lesions. Improved techniques hold promise of improving this diagnostic accuracy.

Abdomen↗
PubMed1993

Accuracy of ultrasound in the diagnosis of acute appendicitis compared with the surgeon's clinical impression.

OBJECTIVE: To compare the accuracy of the surgeon's clinical diagnosis of acute appendicitis with that of an ultrasonographic examination of the abdomen. DESIGN: Prospective trial. SETTING: US Navel Hospital, San Diego, Calif. PATIENTS: One hundred ten patients admitted to the hospital with suspected appendicitis from May 1990 to June 1992. INTERVENTION: Symptoms and signs for each patient were recorded, along with the surgeon's clinical impression of immediate surgery or observation. The patient then underwent an ultrasound examination performed by a staff radiologist. On the basis of the ultrasound findings the patient was placed into one of three categories: appendicitis, normal examination results, or other conditions. Patients with an ultrasound-based diagnosis of appendicitis proceeded to the operation, regardless of the surgeon's clinical impression. Those with other conditions diagnosed with ultrasonography were treated as was appropriate for the condition. RESULTS: The ultrasound-derived diagnosis of appendicitis had a sensitivity of 85.5%, a specificity of 84.4%, a positive predictive value of 88.3%, a negative predictive value of 80.1%, and an overall accuracy of 85.0%. The surgeon's clinical impression at the time of admission had a sensitivity of 62.9%, a specificity of 82.2%, a positive predictive value of 82.9%, a negative predictive value of 61.7%, and an overall accuracy of 71.2%. CONCLUSION: The overall accuracy of ultrasonography in the diagnosis of appendicitis was statistically superior to that of the surgeon's clinical impression (P < .0001). However, 24% of the patients with normal ultrasound findings were ultimately found to have appendicitis at operation, emphasizing the point that ultrasonography cannot be relied on to the exclusion of the surgeon's careful and repeated evaluation.

Acute Disease↗
PubMed2000

Brief communication: a study of the predictive accuracy of mandibular ramus flexure as a singular morphologic indicator of sex in an archaeological sample.

Loth and Henneberg ([1996] Am J Phys Anthropol 99:473-485) assert that they have discovered a single morphologic indicator of sexual dimorphism in the human mandible that rivals the predictive accuracy of the complete pelvis at 94.2% for all samples (99% for healthy samples). To test the accuracy of their method, mandibles (n = 150) from the Tepe Hissar collection were assessed for the presence or absence of mandibular ramus flexure. These results were then compared to a separate sex assessment based on morphologic indicators from the corresponding skull and innominates (where possible) to yield an overall accuracy of only 78.2%. As a means of independent assessment, the mandibular results were also compared with Krogman's ([1940] Racial Types from Tepe Hessar, Iran, from late fifth to early second millennium, BC. Amsterdam: Koninkliijke Nederlandsche Akademie van Wetenschappen) assessment of sex based on craniofacial measurements and morphologic indicators from the skull. This comparison produced an even lower accuracy of 67.2%. Such results question the predictive potential of mandibular ramus flexure as a single indicator of sexual dimorphism and suggest caution when applying this method, especially in the case of fragmentary forensic and fossil remains.

Anthropology, Physical↗
PubMed1997

The accuracy of ultrasound evaluation of amniotic fluid volume in singleton pregnancies: the effect of operator experience and ultrasound interpretative technique.

The objective of this study was to evaluate the effect of operator experience and ultrasound interpretation technique on the accuracy of ultrasound estimates of amniotic fluid volume. Ultrasound evaluation was carried out by an obstetric resident, a nurse sonographer, a maternal-fetal medicine fellow, and a maternal-fetal medicine staff member to subjectively estimate (visual interpretation without sonographic measurements) amniotic fluid volume in 63 pregnancies. Amniotic fluid volume was also evaluated using ultrasound measurements based on the largest vertical pocket technique, the amniotic fluid index, and the two-diameter pocket method. The accuracy of these ultrasound estimates was assessed by comparing the ultrasound results to actual amniotic fluid volume as determined by a dye-dilution technique. For analysis, amniotic fluid volumes were classified as oligohydramnios, normal, or hydramnios using established volumetric criteria for singleton pregnancies. Subjective estimates ranged from 65% to 70% correct and did not differ by operator experience except for the more accurate diagnosis of hydramnios by the maternal-fetal medicine staff. The three sonographic measurements were similar in overall accuracy (59-67%). The two-diameter pocket method was, however, significantly more accurate in identifying oligohydramnios. It appears that neither operator experience nor sonographic technique greatly affects the accuracy of ultrasound estimates of amniotic fluid volume.

Adolescent↗
PubMed1998

Accuracy of side-chain prediction upon near-native protein backbones generated by Ab initio folding methods.

The ab initio folding problem can be divided into two sequential tasks of approximately equal computational complexity: the generation of native-like backbone folds and the positioning of side chains upon these backbones. The prediction of side-chain conformation in this context is challenging, because at best only the near-native global fold of the protein is known. To test the effect of displacements in the protein backbones on side-chain prediction for folds generated ab initio, sets of near-native backbones (< or = 4 A C alpha RMS error) for four small proteins were generated by two methods. The steric environment surrounding each residue was probed by placing the side chains in the native conformation on each of these decoys, followed by torsion-space optimization to remove steric clashes on a rigid backbone. We observe that on average 40% of the chi1 angles were displaced by 40 degrees or more, effectively setting the limits in accuracy for side-chain modeling under these conditions. Three different algorithms were subsequently used for prediction of side-chain conformation. The average prediction accuracy for the three methods was remarkably similar: 49% to 51% of the chi1 angles were predicted correctly overall (33% to 36% of the chi1+2 angles). Interestingly, when the inter-side-chain interactions were disregarded, the mean accuracy increased. A consensus approach is described, in which side-chain conformations are defined based on the most frequently predicted chi angles for a given method upon each set of near-native backbones. We find that consensus modeling, which de facto includes backbone flexibility, improves side-chain prediction: chi1 accuracy improved to 51-54% (36-42% of chi1+2). Implications of a consensus method for ab initio protein structure prediction are discussed.

Models, Chemical↗
PubMed1998

Capillary electrophoresis/electrospray ionization high mass accuracy time-of-flight mass spectrometry for protein identification using peptide mapping.

Capillary electrophoresis/electrospray ionization (CE/ESI) high mass accuracy time-of-flight mass spectrometry was used for the first time to characterize small proteins using peptide mapping. To identify small proteins, the intact proteins were first analyzed to obtain their average molecular weights with errors less than 1 Da. On-line capillary electrophoresis mass spectrometry of the tryptic digests of these small proteins was then performed to obtain the accurate molecular weights of the peptides with accuracies of approximately 10 ppm. Next, this information was used for the identification of the proteins using a protein database. It was found that high mass accuracy is an effective tool in reducing the list of most-likely proteins generated by the database. In addition, on-line collision-induced dissociation of the completely or partially resolved capillary electrophoresis peaks of the protein digests was used to unambiguously identify the sequences of these peptides. Each CE/ESI-MS analysis used only 5 nL of sample containing approximately 120 fmol of each peptide in protein digests. The results indicate that the combination of capillary electrophoresis and high resolution, high mass accuracy time-of-flight mass spectrometry is a viable option for the identification of small proteins using peptide mapping.

Calibration↗
PubMed1999

Using a combination of reference tests to assess the accuracy of a new diagnostic test.

Often the accuracy of a new diagnostic test must be assessed when a perfect gold standard does not exist. Use of an imperfect reference test biases accuracy estimates of the new test. This paper reviews existing approaches to this problem including discrepant resolution and latent class analysis. Deficiencies with these approaches are identified. A new approach is proposed that combines the results of several imperfect reference tests to define a better reference standard. We call this the composite reference standard (CRS). Using the CRS, accuracy can be assessed using multi-stage sampling designs. Maximum likelihood estimates of accuracy and expressions for the variance of sensitivity and specificity are provided. Data from clinical literature on the detection of Chlamydia trachomatis are used to illustrate and compare the different approaches. Advantages of the CRS relative to other approaches include that the CRS is explicitly defined, does not depend on the results of the new test under investigation, and is easy to interpret.

Cell Culture Techniques↗
PubMed1986

Diagnostic accuracy of ultrasonography for hepatocellular carcinoma.

Accuracy of ultrasonography for the diagnosis of hepatocellular carcinoma (HCC) was examined. The subjects were 5339 patients who underwent ultrasonography of the upper abdomen, during the year 1980 at our hospital. Out of 5339, 113 cases were found to be hepatocellular carcinoma by a 3-year follow-up study, checking against the records of regional cancer registry. Diagnostic accuracy based on 6 months of follow-up was as follows: for identification of liver tumors, sensitivity, specificity, and overall accuracy were 94.9%, 98.7%, and 98.9% respectively; for diagnosis of HCC, sensitivity, specificity, and overall accuracy were 58.9%, 99.9%, and 99.3% respectively. In conclusion, the ability of ultrasonography to detect hepatocellular carcinoma is adequately high, and thus, ultrasonography can be employed as a diagnostic procedure for mass screening.

Carcinoma, Hepatocellular↗
PubMed2003

Diagnostic accuracy and pitfalls in fine-needle aspiration interpretation of Warthin tumor.

BACKGROUND: Despite its well-defined histologic appearance, the often variegated cytomorphologic appearance of Warthin tumor (WT) on fine-needle aspiration (FNA) may lead to an erroneous cytopathologic interpretation. In this study, the authors analyzed the potential sources of diagnostic errors and overall accuracy of FNA diagnosis of WT. METHODS: A retrospective search of The Johns Hopkins Hospital Surgical Pathology files (1985-2001) revealed 97 patients with WT, including 31 patients who underwent prior FNA. A comprehensive review of cytopathologic material was undertaken to calculate the overall accuracy of FNA and to identify sources of diagnostic error. RESULTS: All tumors presented in the parotid gland. Four tumors (13%) were deemed inadequate for interpretation due to insufficient material. The FNA diagnosis of WT was rendered in only 20 tumors (74%). The remaining 7 tumors (26%) were misdiagnosed on FNA as consistent with or suspicious for carcinoma or some other neoplastic process. A retrospective review of the tumors, which were over-called on FNA, showed a predominance of necrotic or cellular debris (n = 6 tumors; 22%), significant epithelial metaplasia with atypia (n = 4 tumors; 15%), background inflammation suspicious for tumor diathesis (n = 3 tumors; 11%), spindle cells (n = 1 tumor; 4%), and abundant mucin with keratinized squamous cells (n = 1 tumor; 4%). CONCLUSIONS: FNA is moderately accurate for diagnosing WT, with a 74% accuracy rate in the current series. Cytologic misinterpretation may occur due to a lack of characteristic cytomorphologic features of WT and overabundance of one or more of the following: squamous metaplasia/atypia, mucoid/mucinous background, spindle-shaped cells, and cystic/inflammatory debris. An adequate awareness of these potential sources of erroneous diagnoses, coupled with appropriate clinical findings, may result in a higher accuracy rate.

Adenolymphoma↗
PubMed2005

The incremental effect of positron emission tomography on diagnostic accuracy in the initial staging of esophageal carcinoma.

BACKGROUND: The purpose of the current study was to assess whether [18F]fluorodeoxyglucose positron emission tomography (FDG-PET) provides incremental value (e.g., additional information on lymph node involvement or the presence of distant metastases) compared with computed tomography (CT) in patients with esophageal carcinoma. METHODS: The authors examined 149 consecutive patients with thoracic esophageal carcinoma. Eighty-one patients underwent radical esophagectomy without pretreatment, 17 received chemoradiotherapy followed by surgery, 3 underwent endoscopic mucosal resection, and the remaining 48 patients received definitive radiotherapy and chemotherapy. The diagnostic accuracy of FDG-PET and CT was evaluated at the time of diagnosis. RESULTS: The primary tumor was visualized using FDG-PET in 119 (80%) of 149 patients. Regarding lymph node metastases, FDG-PET had 32% sensitivity, 99% specificity, and 93% accuracy for individual lymph node group evaluation and 55% sensitivity, 90% specificity, and 72% accuracy for lymph node staging evaluation. PET exhibited incremental value over CT with regard to lymph node status in 14 of 98 patients who received surgery: 6 patients with negative CT findings were eventually shown to have lymph node metastases (i.e., they had positive PET findings and a positive reference standard [RS]); 6 patients with positive CT findings were shown not to have lymph node metastases (i.e., they had negative PET findings and a negative RS); and 2 patients were shown to have cervical lymph node metastases in addition to mediastinal or abdominal lymph node metastases. Among the remaining patients, PET showed incremental value over CT with regard to distant organ metastases in six patients. The overall incremental value of PET compared with CT with regard to staging accuracy was 14% (20 of 149 patients). CONCLUSIONS: FDG-PET provided incremental value over CT in the initial staging of esophageal carcinoma. At present, combined PET-CT may be the most effective method available for the preoperative staging of esophageal tumors.

Adult↗
PubMed2006

Comparison of the accuracy of magnetic resonance imaging and positron emission tomography/computed tomography in the presurgical detection of lymph node metastases in patients with uterine cervical carcinoma: a prospective study.

BACKGROUND: The objective of the current study was to determine the accuracy of magnetic resonance imaging (MRI) and positron emission tomography/computed tomography (PET/CT) for detecting lymph node metastases in patients with uterine cervical carcinoma compared with thin-section histopathologic results from systemic lymphadenectomy. METHODS: Twenty-two patients with International Federation of Obstetrics and Gynecology (FIGO) Stage IB-IVA cervical carcinoma who underwent both MRI and PET/CT before lymphadenectomy were included in this study. Lymphadenectomy involved removing all visible lymph nodes in the surgical fields. To enable region-specific comparisons, paraaortic and pelvic lymph nodes were divided into seven regions: the paraaortic area, both common iliac areas, both external iliac areas, and both internal iliac/obturator areas. Histopathologic evaluation of lymph nodes was the diagnostic standard. Chi-square analysis was used to compare the accuracy of MRI and PET/CT for the detection of metastatic lymph nodes. A P value < or = 0.05 was considered statistically significant. RESULTS: With MRI, the sensitivity, specificity, and accuracy rates for detecting metastatic lymph nodes in each lymph node group were 30.3% (10 of 33 lymph node groups), 92.6% (112 of 121 lymph node groups), and 72.7% (122 of 154 lymph node groups), respectively; with PET/CT, those rates were 57.6% (19 of 33 lymph node groups), 92.6% (112 of 121 lymph node groups), and 85.1% (131 of 154 lymph node groups), respectively. Statistical analysis showed that PET/CT was more sensitive than MRI (P = 0.026) but that there were no statistical differences noted with regard to specificity (P = 1.000) or accuracy (P = 0.180). Power analysis demonstrated that a sample size of 685 lymph node groups (98 patients) would be necessary to demonstrate that PET/CT was more accurate than MRI (alpha = 0.05; beta = 0.80). CONCLUSIONS: PET/CT was more sensitive than MRI for detecting lymph node metastases in patients with uterine cervical carcinoma.

Adult↗
PubMed1992

Accuracy of bronchial aspiration cytology in typing operable (stage I-II) pulmonary carcinomas.

The accuracy of bronchial aspiration cytology in typing resectable (stage I-II) lung cancer has been investigated in 100 cases, comparing preoperative cytologic features with pulmonary tumor histology seen at surgery. The accuracy has been 100% for small-cell carcinoma (two cases), 98.8% for squamous-cell carcinoma (86 cases), and 91.6% for adenocarcinoma (12 cases). The overall accuracy rate has been 98%. No case of undifferentiated large-cell carcinoma has been identified. It is suggested that the high accuracy in cytologic typing of operable lung cancer is basically related to adequate preservation of differentiation features, thus allowing for correct identification of most non-small-cell carcinoma. Moreover, the absence in this study of any large-cell carcinoma, compared with its frequency in advanced stage series, would indicate that such a histotype reflects excessive dedifferentiation of an original squamous or glandular form.

Adenocarcinoma↗