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PubMed1997

Management of patients with angina pectoris by GPs: a study with standardized (simulated) patients in actual practice.

BACKGROUND: Little is known about the management of patients with angina pectoris by GPs. OBJECTIVE: The purpose of this study was to assess how a group of GPs managed a patient with angina pectoris complaints in a real-life practice setting during unbiased consultations with standardized patients. METHODS: GPs were consulted during normal surgery hours by a standardized patient portraying a patient with angina pectoris. The setting was Trondheim, Norway. All 87 GPs in the city of Trondheim (Norway) were informed by letter about a study with standardized patients and invited to take part. They were asked to give consent to be visited during actual surgery hours by standardized patients. The date, number and content of the visits planned were not mentioned. They were not told that the study focused on angina pectoris. For budgetary reasons it was decided to ask 24 physicians to participate. The GPs were consulted during normal surgery hours by a standardized patient portraying a patient with angina pectoris. The patients reported on the consultations using a checklist based on guidelines for management of angina pectoris. Outcome measures were the content and number of actions undertaken from the guidelines. RESULTS: Twenty-eight GPs (32%) agreed to participate. Of these, 24 were selected and visited. One doctor detected the standardized patient. The results showed that the participating physicians met 76% of the guidelines used. However, the GPs ordered 31 different types of laboratory test (mean = 7.9, range = 1-18 per physician). In addition, the 23 consultations resulted in seven referrals (two for chest X-rays, four for an exercise test and one referral to a specialist in cardiology). Twenty-two of the 23 doctors made the correct diagnosis and informed the patient accordingly. CONCLUSIONS: When assessed in an unbiased situation in real practice, GPs performed well against a pre-set standard for management of angina pectoris patients. Much variation was found in the request for laboratory tests. These real-life practice data suggest that there is a need for discussing guidelines for effective ordering of laboratory tests in general practice.

Aged↗
PubMed2000

Experts recommend minimum nurse staffing standards for nursing facilities in the United States.

The experts concluded that current data show that the average nurse staffing levels (for RNs, LVN/LPNs, and NAs) in nursing homes are too low in some facilities to provide high quality of care. Caregiving, the central feature of a nursing home, needs to be improved to ensure high quality of care to residents. Because detailed time studies have not been conducted on the amount of time that is required to provide high quality of care to residents, expert opinion is currently the best approach to addressing the problem of inadequate staffing. Increases in the education level and training of nursing staff are also strongly recommended as a step to improving quality of care and reducing turnover rates in nursing homes. These recommendations are designed for consideration by Congress, HCFA regulators, policymakers, nursing home administrators, and nurses. Ideally, Congress would pass legislation establishing these recommendations as minimum standards for all nursing homes or direct HCFA to establish detailed minimum nurse staffing standards to ensure that staffing levels take into account the number and the case-mix of the residents. Alternatively, HCFA could introduce minimum staffing standards through the regulatory process. In 1999 there were a number of efforts at the state level to increase minimum staffing levels. Mohler (1999) surveyed selected states and found that 21 states had either proposed new legislation or were considering proposals for new legislation or new regulations. In California, for example, in 1999 the state budget approved $31 million in new state funds (to be matched with $31 million in federal Medicaid dollars) to increase nursing home staffing minimum requirements from 2.8 to 3.2 hr per resident day and to increase wage rates. Overall, nursing facilities need to be held accountable by HCFA for providing adequate levels and types of staffing to meet the needs of their residents, especially because government is paying for 61% of the expenditures. Adopting these minimum standards will have an important impact on improving the quality of the nation's nursing home care. Additional research is needed to determine appropriate levels and types of staff to provide high quality of care to residents. These studies could test the proposed staffing standards against existing staffing levels to examine the impacts on quality. As new data become available on staffing levels, revisions of staffing standards should be made if necessary to ensure that high standards are maintained.

Aged↗
PubMed2004

What is the most relevant standard of success in assisted reproduction? Is there a single 'parameter of excellence'?

An optimal standard of success reflects all risk and safety aspects of the treatment-related procedures. In this debate, we question whether one single standard of success can cover the complexity of assisted reproduction technology (ART). To emphasize the use of different parameters as standards of success, we calculated data from all IVF and ICSI cycles initiated at the Fertility Clinic, Rigshospitalet, Copenhagen, Denmark between 1999 and 2001. Several already established parameters were computed and, additionally, new suggestions for end-points were calculated. Three parameters were proposed as the best standards of success in ART: (i) number of oocytes per aspiration (8.7); (ii) number of ongoing implantations per embryo transferred (20%); and (iii) number of deliveries per embryo transferred (14%). These parameters cover aspects of all steps in ART, i.e. the stimulation, laboratory and embryo transfer/outcome phase, also termed the pre-in vitro, in vitro and post-in vitro phase. We suggest that the final description of an ART programme should be a balanced choice of the three standards of success proposed herein. If these standards are implemented as national gold standards, the future goal of homogeneous reporting of success rates in ART is within reach.

Female↗
PubMed1996

Child mortality following standard, medium or high titre measles immunization in West Africa.

BACKGROUND: The World Health Organization (WHO) recommended the use of high titre measles vaccine in 1989. Subsequent long term follow-up of several trials yielded results suggesting higher mortality among children inoculated with medium and high titre vaccines compared to standard titre vaccines, although none of the individual trials found significant differences in mortality. METHODS: Long term survival after standard, medium and high titre measles vaccines has been investigated in a combined analysis of all West African trials with mortality data. In trials from Guinea-Bissau, The Gambia and Senegal, children received medium or high titre vaccines from 4 months of age and were compared to control groups recruited at the same time later receiving standard titre vaccine from 9 months of age. All children were followed up to at least 3 years old. RESULTS: Combining trials of high titre vaccines showed higher mortality among the high titre group compared to the standard group: mortality ratio (MR) = 1.33 (95% CI : 1.02-1. 73). Mortality among recipients of medium titre vaccines was not different from that in the standard vaccine group, MR = 1.11 (95% CI: 0.54-2.27). In a combined analysis by sex, the adjusted mortality ratios comparing high titre vaccine with standard vaccine were 1.86 (95% CI : 1.28-2.70) for females and 0.91 (95% CI : 0.61-1.35) for males. The trials were not designed to study long term mortality. Adjustments for several possible sources of bias did not alter the results. CONCLUSIONS: The combined analysis showed a decreased survival related to high titre measles vaccine compared with standard titre vaccines, though solely among females. As a result of these studies from West Africa and a study from Haiti, WHO has recommended that high titre measles vaccine no longer be used.

Age Distribution↗
PubMed1989

Individualized pharmacokinetic versus standard dosing of amikacin: a comparison of therapeutic outcomes.

We compared the therapeutic outcome in patients with normal renal function managed with either individualized pharmacokinetic (PK) dosing or standard (every 12 h) dosing of amikacin. A total of 82 patients with confirmed or suspected infectious processes were entered into the study. There was no difference in therapeutic outcomes (P = 0.47) with one patient from each group dying. The duration of hospital stay (15.8 days vs 11.3 days, P = 0.052) and the mean duration of therapy (8.9 days vs 7.4 days, P = 0.20) were not significantly different, although a trend was seen towards longer time periods in the PK group. The incidence of nephrotoxicity (3 vs 1, P = 0.61), and calculated PK parameters were not different between the PK and standard groups, respectively. Upon evaluation of amikacin serum concentrations in individual patients, we found that five of 82 patients (6.1%) were or might have been at risk for toxicity with standard, unmonitored doses of amikacin, when compared to published literature. Although equivalent therapeutic outcomes may be achieved with standard or individualized PK dosing, the risk of toxicity with standard dosing is substantial. The routine use of standard dosing regimens cannot be recommended. Definition of specific patients subtypes in whom standard regimens utilizing lower doses can safely and effectively be used is necessary.

Adolescent↗
PubMed2001

Randomized phase I study of standard-fractionated or accelerated-hyperfractionated radiotherapy with concurrent cisplatin and vindesine for unresectable non-small cell lung cancer: a report of Japan Clinical Oncology Group Study (JCOG 9601).

BACKGROUND: We attempted dose escalation of standard-fractionated and accelerated-hyperfractionated radiotherapy combined with concurrent cisplatin and vindesine to improve local control and survival in unresectable non-small cell lung cancer. METHODS: Twenty-one patients were enrolled between June 1996 and August 1997. There were 19 males and two females and their median age was 65 years (range 45-74 years). Performance status was 0 in 10 cases and 1 in 11 cases. Disease stage was IIIA in three cases and IIIB in 18 cases. The cases were randomized to a standard-fractionated arm (n = 10) or an accelerated-hyperfractionated radiotherapy arm (n = 11) with two or three cycles of concomitant cisplatin 80 mg/m(2) on day 1 and vindesine 3 mg/m(2) on days 1 and 8 every 4 weeks in both arms. Dose escalation from 60 Gy/30 fractions/6 weeks to 70 Gy/35 fractions/7 weeks was planned in the standard-fractionated radiotherapy group and from 54 Gy/36 fractions/3.6 weeks to 60 Gy/40 fractions/4 weeks and then 66 Gy/44 fractions/4.4 weeks in the accelerated-hyperfractionated radiotherapy group. RESULTS: Grade 3 or 4 hematological toxicities were observed as follows: in the standard-fractionated/accelerated-hyperfractionated radiotherapy group, leukocytopenia 9/10, anemia 2/3 and thrombocytopenia 0/2. Grade 3 non-hematological toxicity consisted of esophagitis 0/3, increased serum total bilirubin 2/0 and hypoxia 0/1. Two patients died of radiation pneumonitis in the standard-fractionated radiotherapy group. Dose-limiting toxicity was observed in four of the 10 and seven of the 11 patients at initial dose level of standard-fractionated radiotherapy, 60 Gy/30 fractions/6 weeks, and of accelerated-hyperfractionated radiotherapy, 54 Gy/36 fractions/3.6 weeks, respectively. Thus, we failed to escalate the dose of radiotherapy in both arms. The overall response rate in the standard-fractionated group and the accelerated-hyperfractionated radiotherapy group was 70 and 73% and the 1-year survival rate was 70 and 64%, respectively. CONCLUSIONS: We concluded that these schedules of radiotherapy with concurrent cisplatin and vindesine were unacceptable for use in patients with unresectable non-small cell lung cancer. Further modifications of the schedule for radiotherapy and evaluation of combination with new chemotherapy are warranted.

Aged↗
PubMed1997

Measurement error correction for logistic regression models with an "alloyed gold standard".

Recently, some authors have questioned the validity of methods which correct relative risk estimates for measurement error and misclassification when the "gold standard" used to obtain information about the measurement error process is itself imperfect. When such an "alloyed" gold standard is used to validate the usual exposure measurement, the bias in the "regression calibration" (Rosner et al., Stat Med 1989; 8:1051-69) measurement-error correction factor for relative risks estimated from logistic regression models is derived. This quantity is a function of the correlations of the "alloyed" gold standard (X) and the usual exposure assessment method (Z) with the truth, of the ratio of the variances of X and Z, and of the correlation between the errors in the "alloyed" gold standard and the errors in the usual exposure assessment method. In this paper, it is proven that if the errors between Z and X are uncorrelated, the regression calibration method has no bias even when the gold standard is "alloyed." When a third method of exposure assessment is available and it is reasonable to assume that the errors in this method are uncorrelated with the errors in the other two exposure assessment methods, point and interval estimates of the correlation between the errors in X and Z are derived. These methods are illustrated here with data on the measurement of physical activity, vitamins A and E, and poly- and monounsaturated fat. In addition, when a third exposure assessment method is available, a modification of standard regression calibration is derived which can be used to calculate point and interval estimates of relative risk that are corrected for measurement error in both X and Z. This new method is illustrated here with data from the Health Professionals Follow-up Study, a study investigating the associations between physical activity and colon cancer incidence and between vitamin E intake and coronary heart disease. It is shown that in these examples, correlations of the errors in X and Z tended to be small. Even when moderate, estimates of relative risk corrected for error in both X and Z were not very different from the estimates which assumed that X was a true gold standard.

Bias↗
PubMed1999

Standardized lifetime risk.

The authors propose the use of two new standardized measures of risk, the standardized lifetime risk and the standardized number of years of life lost. These measures maintain the advantages of standardized rates but are more readily understood without special training. In this paper, standardizing weights based on 1992 data from England and Wales are provided, and the new measures are illustrated with a variety of examples. The new standardized rates are useful for examining trends over time; for comparing the impact of various diseases on public health; and for comparing rates of a given disease in several different countries. The authors think it is far more informative to say that 41 out of every 1,000 women die of breast cancer than to say that the standardized mortality rate is 51 per 100,000 women per year.

Female↗
PubMedDate not supplied

Content and criterion validity evaluation of National Public Health Performance Standards measurement instruments.

OBJECTIVE: The Centers for Disease Control and Prevention's National Public Health Performance Standards Program (NPHPSP) has developed instruments to measure the performance of local and state public health departments on the 10 "Essential Services of Public Health," which have been tested in several states. This article is a report of the evaluation of the content and criterion validity of the local public health performance assessment instrument, and the content validity of the state public health performance assessment instrument. METHODS: Health department performance is measured using a set of indicators developed for the 10 Essential Services of Public Health and a model standard for each indicator. Content validity of each model standard in the local instrument was addressed by community partners along the following dimensions: the importance of each standard as a measure of the associated Essential Service, its completeness as a measure, and its reasonableness for achievement. All standards for each Essential Service were then judged in terms of their completeness in measuring performance in that service. Content validity of the state instrument was evaluated in a group interview of health department staff members from three states. Criterion validity of the local instrument was assessed for a sample of eight public health departments in Florida and six in New York by examining documentary evidence for selected responses. Criterion validity was also evaluated for a sample of Florida local public health departments and one Hawaii public health department by comparing state health department staffs' judgments of performance against the instrument score. RESULTS: Criterion validity was upheld for a summary performance score on the local instrument, but was not upheld for performance judgments on individual Essential Services. The NPHPSP standards based on the Essential Services have validity for measuring local public health system performance, according to community partners. The model standards are valid measures of state performance, according to state public health departments in three states. CONCLUSIONS: Within the scope of the validity evaluations completed, the NPHPSP state and local performance assessment instruments were found to be valid measures of public health performance.

Attitude of Health Personnel↗
PubMed1997

Validating the standardized-patient assessment administered to medical students in the New York City Consortium.

PURPOSE: To test the criterion validity of existing standardized-patient (SP)-examination scores using global ratings by a panel of faculty-physician observers as the gold-standard criterion; to determine whether such ratings can provide a reliable gold-standard criterion to be used for validity-related research; and to encourage the use of these gold-standard ratings for validation research and examination development, including scoring and standard setting, and for enhancing understanding of the clinical competence construct. METHOD: Five faculty physicians independently observed and rated videotaped performances of 44 students from one medical school on the seven SP cases that make up the fourth-year assessment administered at The Morchand Center of Mount Sinai School of Medicine to students in the eight member schools in the new York City Consortium. RESULTS: The validity coefficients showed correlations between scores on the examination and the overall ratings ranging from .60 to .70. The reliability coefficients for ratings of overall examination performance reached the commonly recommended .80 level and were very close at the case level, with interrater reliabilities generally in the .70 to .80 range. CONCLUSION: The results are encouraging, with validity coefficients high enough to warrant optimism about the possibility of increasing them to the recommended .80 level, based on further studies to identify those measurable performance characteristics that most reflect the gold-standard ratings. The high interrater reliabilities indicate that faculty-physician ratings of performance on SP cases and examinations can or may be able to provide a reliable gold standard for validating and refining SP assessment.

Clinical Clerkship↗
PubMed1999

Distortion product otoacoustic emission test performance for a priori criteria and for multifrequency audiometric standards.

OBJECTIVES: 1) To describe distortion product otoacoustic emission (DPOAE) test performance when a priori response criteria are applied to a large set of DPOAE data. 2) To describe DPOAE test performance when multifrequency definitions of auditory function are used. 3) To determine DPOAE test performance when a single decision regarding auditory status is made for an ear, based on DPOAE data from several frequencies. 4) To compare univariate and multivariate test performance when multifrequency gold standard definitions and response criteria are applied to DPOAE data. DESIGN: DPOAE and audiometric data were analyzed from 1267 ears of 806 subjects. These data were evaluated for three different frequency combinations (2, 3, 4 kHz; 2, 3, 4, 6 kHz; 1.5, 2, 3, 4, 6 kHz). DPOAE data were collected for each of the f2 frequencies listed above, using primary levels (L1/L2) of 65/55 dB SPL and a primary ratio (f2/f1) of 1.22. Sensitivity and specificity were evaluated for signal to noise ratios (SNRs) of 3, 6, and 9 dB, which are in common clinical use. In addition, test performance was evaluated using clinical decision theory, following the convention we have used in previous reports on otoacoustic emission test performance. Both univariate and multivariate analyses techniques were applied to the data. In addition to evaluating DPOAE test performance for the case when audiometric and f2 frequency were equal, multifrequency gold standards and multifrequency criterion responses were evaluated. Three new gold standards were used to assess test performance: average pure-tone thresholds, extrema thresholds that took into account both the magnitude of the loss and the number of frequencies at which hearing loss existed, and a combination of the two. These new gold standards were applied to each of the three frequency groups described above. RESULTS: As expected, SNR criteria of 3, 6, and 9 dB never resulted in perfect DPOAE test performance. Even the most stringent of these criteria (9 dB SNR) did not result in a sensitivity of 100%. This result suggests that caution should be exercised in the interpretation of DPOAE test results when these a priori criteria are used clinically. Excellent test performance was achieved when auditory status was classified on the basis of the new gold standards and when either SNR or the output of multivariate logistic regressions (LRs) were used as criterion measures. Invariably, the LR resulted in superior test performance compared with what was achieved by the SNR. For SNR criteria of 3, 6, and 9 dB and (by definition) for the LR, specificity, in general, exceeded 80% and often was greater than 90%. Sensitivity, however, depended on the magnitude of hearing loss. Diagnostic errors, when they occurred, were more common for patients with mild hearing losses (21 to 40 dB HL); sensitivity approached 100% once the hearing loss exceeded 40 dB HL. The largest differences between test performance based on SNR or LR occurred for the ears with mild hearing loss, where the LR resulted in more accurate diagnoses. CONCLUSIONS: It should not be assumed that the use of a priori response criteria, such as SNRs of 3, 6, or 9 dB, will identify all ears with hearing loss. Test performance when multifrequency gold standards are used to define an ear as normal or impaired and when data from multiple f2 frequencies are used to make a diagnosis, resulted in excellent test performance, especially when the LR was used. When predicting auditory status with multifrequency gold standards, the LR resulted in relative operating characteristic curve areas of 0.95 or 0.96. An output from the LR can be selected that results in a specificity of 90% or better. When the loss exceeded 40 dB HL, the same output from the LR resulted in test sensitivity of nearly 100%. These were the best test results that were achieved. (ABSTRACT TRUNCATED)

Acoustic Stimulation↗
PubMed2002

Electromagnetic field standards in Central and Eastern European countries: current state and stipulations for international harmonization.

Electromagnetic field standards in the West are based on well-established acute biological effects that could be considered as signaling a potentially adverse health effect. The specific absorption rate, which is proportional to the tissue heating (thermal effects), represents the basic restriction of exposure to Radio-Frequency (RF) fields. On the other hand, Eastern European standards are designed to protect from potential non-thermal effects that might be caused by chronic exposure to very low intensities, where a so-called "power load" (a product of field intensity and duration of exposure) represents the basic limitation. Thus, electromagnetic field standards in Eastern European countries differ considerably from those which are proposed by the International Commission of Non-ionizing Radiation Protection and the Standards Coordinating Committee 28 of the Institute of Electrical and Electronics Engineers, Inc. In the present paper, the strategies for development of exposure limit values in electromagnetic fields standards currently in force in Eastern and Central European countries are discussed. Some differences as well as similarities of the national health and safety standards and the main obstacles to harmonization of these standards with those being established by Western national and international organizations and agencies are presented.

Electromagnetic Fields↗
PubMed1994

Is a low-osmolarity ORS solution more efficacious than standard WHO ORS solution?

The clinical efficacy of a diluted oral rehydration salts (ORS) solution was compared in a pilot study with that of intravenous (i.v.) therapy and of standard World Health Organization (WHO)/United Nations Childrens Fund (UNICEF) ORS solution in children with acute diarrhea. Sixty-one boys aged 3 to 24 months, admitted to hospital with acute diarrhea and signs of dehydration, were randomly assigned to groups receiving standard ORS solution, diluted ORS solution, or i.v. therapy. In children treated with standard ORS solution and small amounts of plain water, the total fluid intake was 25-39% greater, the stool output was 58-77% greater (p < 0.01), and the duration of diarrhea was 30-55% greater than in the other treatment groups. Intake of plain water, taken separately or added to the ORS solution, was greater in children given diluted ORS solution (73 +/- 23 ml/kg) than in those given standard ORS solution (21 +/- 32 ml/kg) (p < 0.001). The mean serum sodium concentration increased by 2.2 mEq/L in children given standard ORS solution, whereas it decreased by 2.9 mEq/L in those given diluted ORS solution. This study shows that some children develop worsening diarrhea and increasing serum sodium concentrations when treated with standard ORS solution and given only small amounts of plain water. This is probably caused by the slight hypertonicity of standard ORS solution combined with transient partial glucose malabsorption. This can be avoided if water, breast milk, or another low-solute drink is given liberally during maintenance therapy with ORS solution, as recommended by the WHO.

Acute Disease↗
PubMed1998

Variations in standardized hospital mortality rates for six common medical diagnoses: implications for profiling hospital quality.

OBJECTIVES: The authors determined whether standardized hospital mortality rates varied for six common medical diagnoses. METHODS: The retrospective cohort study included 89,851 patients aged 18 years and older discharged from 30 hospitals in a large metropolitan area in 1991 to 1993 with a principal diagnosis of acute myocardial infarction, congestive heart failure, pneumonia, stroke, obstructive lung disease, or gastrointestinal hemorrhage. For each hospital, standardized mortality ratios (observed/predicted mortality) were determined using validated risk-adjustment models that were based on clinical data elements abstracted from patients' hospital records. Hospitals also were categorized into quintiles on the basis of standardized mortality ratios. Correlations between standardized mortality ratios and agreement between quintile rankings were determined for each pair of diagnoses. RESULTS: Correlations between hospital-standardized mortality ratios for individual diagnoses were generally weak. For the 15 possible pairs of diagnoses, Pearson coefficients ranged from -0.10 to 0.43; only six were 0.30 or greater. Agreement between hospital quintile rankings was also generally low, with weighted kappa values ranging from -0.12 to 0.42. Three of 15 kappa values were less than 0 (ie, agreement lower than chance), and only four exceeded 0.20, the threshold for "fair" agreement. Although simulated analyses found that random variation and relatively low hospital volumes accounted for some of the difference in standardized mortality ratios for diagnoses, a large proportion of the difference remained unexplained. CONCLUSIONS: Standardized hospital mortality rates varied for six diagnoses that likely are managed by similar practitioners. Although variability may be decreased by restricting analyses to hospitals with large volumes, the findings indicate that for many hospitals, diagnosis-specific mortality rates may be an inconsistent measure of hospital quality, even when data are aggregated for multiple years.

Adolescent↗
PubMed1992

The legal danger of written protocols and standards of practice.

Nurse practitioners have historically developed protocols and standards of practice to guide and improve the quality of their patient care. Written protocols and standards of practice can, however, create a potential malpractice problem. Lawyers who bring malpractice cases on behalf of patients will use the protocols and standards to measure the practitioner's care. The practice standards are often too high to be reasonably met by practitioners at all times and in all settings. As a result, the practitioner's care may breach those standards. Nurse practitioners should develop protocols that are based on a minimum safe level and not the maximum level aimed at ideal care. Standards and protocols should be updated and realistic. Once developed, protocols and standards must be followed precisely to limit potential liability.

Clinical Protocols↗
PubMed2000

Comparison of hemocytometer leukocyte counts and standard urinalyses for predicting urinary tract infections in febrile infants.

OBJECTIVES: To compare the accuracy of standard and hemocytometer white blood cell (WBC) counts and urinalyses for predicting urinary tract infection (UTI) in febrile infants. METHODS: Enrolled were 230 febrile infants < 12 months of age. All urine specimens were obtained by suprapubic bladder aspiration and microscopically analyzed by the standard urinalysis (UA) and by hemocytometer WBC counts simultaneously, and quantitative urine cultures were performed. Receiver-operating characteristic (ROC) curves were constructed for each method of UA. The optimal cutoff point of the UA test in predicting UTI was determined by ROC analysis. RESULTS: There were 37 positive urine cultures of at least 1,000 CFU/ml. Of these 37 patients, 9 females and 28 males, 1 had a positive blood culture (Escherichia coli). Thirty (81%) of the positive urine cultures had a bacterial colony count > or = 100,000 colony-forming units/ml, whereas the remaining had between 1,000 and 50,000 colony-forming units/ml. The area under the ROC curve for standard UA was 0.790 +/- 0.053, compared with 0.900 +/- 0.039 for hemocytometer WBC counts (P < 0.05). For hemocytometer WBC counts, the presence of < or =10 WBC/microl appeared to be the most useful cutoff point, yielding a high sensitivity (83.8%) and specificity (89.6%). Standard UA, with a cutoff point of 5 WBC/high power field, had a lower sensitivity (64.9%) and similar specificity (88.1%). The hemocytometer WBC counts showed significantly greater sensitivity and positive predictive value (83.8 and 60.8%, respectively) than the standard urinalysis (64.9 and 51.1%, respectively) (P < 0.05). The accuracy, specificity and likelihood ratio of hemocytometer WBC counts were also greater than that of standard UA (88.7, 89.6 and 8.08% vs. 84.3, 88.1 and 5.44%). CONCLUSION: Hemocytometer WBC counts provide more valid and precise prediction of UTI in febrile infants than standard UA. The presence of > or =10 WBC/microl in suprapubic aspiration specimens is the optimum cutoff value for identifying febrile infants for whom urine culture is warranted.

Chi-Square Distribution↗
PubMed2002

Comparison of two rapid Streptococcus pyogenes diagnostic tests with a rigorous culture standard.

BACKGROUND: Comparisons of rapid antigen tests for the diagnosis of pharyngitis are often made between published studies but may not be reliable given differences in study design, sampling and reference standard definitions. Tests are rarely compared against each other in a single study. METHODS: The sensitivity and specificity of two rapid diagnostic tests were compared against a multiplate culture standard defined as the identification of on any of four culture plates. Paired swabs were tested for antigen using Genzyme's OSOM Ultra Strep A Test and compared with Biostar's Strep A OIA Max Test. RESULTS: Ninety-four (31.1%) of 302 matched samples were identified with The sensitivity of Genzyme's OSOM Ultra Strep A Test against the multiplate culture standard was 92.6%, significantly higher ( P= 0.001) than that (75.5%) of Biostar's Strep A OIA Max Test. Specificities were 92.8 and 97.1%, respectively. Data analysis of culture results and statistical modeling showed that cultures of two or more samples are necessary for a sensitivity of 95% or greater for a comparison standard compared with true disease status. CONCLUSIONS: When comparing the performance of rapid antigen tests for pharyngitis, a rigorous culture standard should be used consisting of at least two separate samples (swabs and/or pledgets), ultimately plated on selective agar. Genzyme's OSOM Ultra Strep A Test was significantly more sensitive than Biostar's Strep A OIA Max Test in comparison with a multiplate culture standard and a same swab, single plate culture standard.

Antigens, Bacterial↗
PubMed1983

Cancer II. Distortions in standardized rates.

Age-adjustment (standardization), the statistical method most used by cancer epidemiologists to express incidence and mortality rates, makes use of an arbitrarily chosen "standard" population to calculate rates that are in reality only abstract index numbers. It is generally known that the "age" of any standard population affects the magnitude of the index, but it is not widely recognized that the use of U.S. Censuses as standards, possibly excepting the 1930 U.S. Census population, distorts the index number. The greater the disparity between the numbers of males and females in middle-aged groups and older, the greater is the distortion. Hence sex as well as age distribution in a standard must be considered if rates are to be expressed in terms of sex. Trends of cancer incidence or mortality will have different slopes depending on the census year chosen as a standard; yet no standard can arbitrarily be called the "correct" one. Age-, race-, and sex-specific rates are more precise and can be made to give considerably more meaningful description of cancer trends, albeit their use requires scrutiny of a greater assortment of numbers.

Actuarial Analysis↗