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Predictive value of in vitro tests for the IgE-dependent and the IgE-independent anaphylactoid reactions to muscle relaxants.

Several aspects of in vitro tests for life-threatening anaphylactoid reactions (AR) to neuromuscular blockers (NMB, muscle relaxants) were addressed and highlighted. They include topics which have been under study in our centre in the past few years. Already available tests and newly developed ones were assessed for diagnostic and predictive value, as well as for usefulness in understanding of mechanism(s) of AR. The theoretical and practical aspects of radioallergosorbent tests (RAST) for antibodies to NMB (particularly IgE), their predictive value and their possible use in "screening" with the hope of preventing AR are discussed. Confirmatory tests after AR include plasma or serum histamine/methylhistamine, tryptase and possibly eosinophil cationic protein (ECP), all of which point to activation of mast cells, basophils, eosinophils and possibly other inflammatory cells. Future anesthetics after AR can be guided by measurement of the in vitro release of histamine, leukotrienes and possibly eosinophil cationic protein (ECP) and serum antibodies. Antibody studies (mainly IgE by RAST) are valuable for diagnosis and, together with other tests, can throw light on cross-reaction and further clarify the mechanisms of AR. In RAST (IgE)-negative cases of AR, which may be due to immune or nonimmune mechanisms, mediator release measurements are particularly useful. Lymphocyte stimulation tests may also be useful in such cases. RASTs cannot be advocated for general preoperative screening, as yet. Further development or selection of potentially "susceptible" subpopulations may improve the predictive value of these tests.

Anaphylaxis↗

Age-related physical fitness and the predictive values of fitness tests for work ability in home care work.

Despite the widespread assessment of physical fitness in occupational medicine and health services, only a few validity studies have been made of the fitness tests used in relation to job demands. The purpose of this study was to assess the physical fitness of female home care workers (n = 132) in relation to age and to evaluate whether the fitness tests used predict work ability over a 5-year period of follow-up. Muscle endurance declined by 18% to 37%, and isometric muscle strength by 10% to 18%, from the youngest (21 to 35 years) to the oldest (45 to 59 years) age group. The proportion of those subjects who could be classified below the average age-related fitness categories according to the maximal oxygen consumption was highest (50%) for the 21-to-35 age group. The logistic regression model showed that obesity (odds ratio [OR] = 7.51) and poor results on the sit-up (OR, 8.9), balance (OR, 6.5), and weight-lifting (OR, 4.6) tests predicted the highest risk for reduced work ability, according to the work ability index used in the 5-year follow-up. Moreover, average results for the trunk side-bending test (OR, 4.6), poor results for the squatting test (OR, 3.8), poor knee extension strength (OR, 4.2), and the average maximal oxygen consumption (l.min-1) (OR, 3.1) indicated a high risk for reduction in work ability. The physical fitness tests were strongly associated with the physical demands of home care work and were relevant for the evaluation of work-related fitness among home care workers.

Adult↗

Breath hydrogen excretion as a screening test for the early diagnosis of necrotizing enterocolitis.

We measured breath H2 excretion in 122 neonates from birth to 1 month of age. The patients weighed less than 2000 g at birth and thus were at risk for developing necrotizing enterocolitis (NEC). Hydrogen excretion was normalized for the quality of the expired air by dividing by the carbon dioxide pressure of the gas sample. The mean (+/- SD) peak H2/CO2 ratio was significantly different between the seven patients who subsequently developed NEC (9.4 +/- 2.7 ppm/mm Hg) and the 115 patients who did not (5.0 +/- 3.5 ppm/mm Hg). The prevalence of NEC was 5.7% in the present study. Defining a positive test as one with a ratio value of greater than or equal to 8.0 ppm/mm Hg, the resulting screening test had a sensitivity of 86% and a specificity of 90%. The screening test yielded a 33% predictive value of a positive test and a 99% predictive value of a negative test. High H2 excretion occurred eight to 28 hours before the earliest clinical signs of NEC. Breath H2 excretion is a simple noninvasive test that may be useful in the management of the premature neonate at risk for the development of NEC.

Breath Tests↗

Prostate specific antigen ratio: for diagnosis and assessment of aggressiveness of malignancy of prostate.

The search for a perfect tumour marker, which would be able to distinguish benign from malignant enlargement of prostate accurately, is still not complete. Total Prostate Specific Antigen (TPSA), a good test, has it's own inadequacies but Free Prostate Specific Antigen (FPSA) to TPSA ratio is emerging as a better adjuvant to it. This prospective study was done to verify the utility of FPSA to TPSA ratio in diagnosis of malignancy of prostate and its relationship to Gleason grading (indicating the aggressiveness) of adenocarcinoma of prostate. 100 patients with urinary symptoms, who were above fifty years of age and had prostatic enlargement, formed the study group. TPSA and FPSA were assayed by ELISA method and FPSA to TPSA ratio was calculated. Prostatic biopsy of all the cases was obtained and diagnostic histopathology and Gleason grading (in cases where adenocarcinoma was diagnosed) was done. Sensitivity, specificity, predictive value of positive test and predictive value of negative test for TPSA and FPSA to TPSA ratio were calculated. They were found to be 100%, 76.7%, 74.1% and 100% for TPSA and 82%, 100%, 100%, 89% for FPSA/TPSA ratio. Thus making it very obvious that FPSA to TPSA ratio is an excellent adjuvant to TPSA for diagnosis of malignancy of prostate increasing the specificity and predictive value for positive test. An inverse correlation (correlation coefficient = -0.95) was also found between PSA ratio and aggressiveness of prostate cancer, pointing towards its capability to predict the histological (Gleason) grade of the tumour.

Adenocarcinoma↗

[Predictive value of preoperative acidity tests in ulcer recurrence after supraselective vagotomy].

The authors have analysed the predictive value of the basal and peak gastric acidity levels, measured preoperatively, in a series of 27 supraselective vagotomies. They recommend care in the choice of this operation for hypersecretors and they propose criteria for the preoperative selection of the candidates. They suggest determination of the preoperative basal gastric acidity level and a cimetidine suppression test to identify patients at high risk for recurrence of the ulcer.

Adult↗

Ultrasonography as a method of screening for tracheal invasion by papillary thyroid cancer.

PURPOSE: To assess the reliability of ultrasonography (US) for detecting tracheal invasion by papillary thyroid cancer (PTC). METHODS: We reviewed the clinical and surgical data of 509 patients who underwent surgery for primary PTC during 2003, after routine preoperative US. RESULTS: Ultrasonography showed possible tracheal invasion in 43 of the 509 patients. However, the US findings could not be evaluated in 32 patients because of high tumor calcification, a tumor diameter greater than 4 cm, or tumor extension inferior to the clavicle. We shaved the tracheal wall in 11 patients and resected the tracheal wall in 2 patients. The sensitivity of US for diagnosing of tracheal invasion was 91%, the specificity 93%, the predictive value of a positive test 25%, the predictive value of a negative test 99%, and the accuracy 93%. CONCLUSION: Ultrasonography is a useful method of screening for tracheal invasion. A negative sonogram is a reliable indicator of the absence of tracheal invasion, except when tumors are highly calcified or extend inferior to the clavicle.

Adenocarcinoma, Papillary↗

Mexiletine and tocainide: a comparison of antiarrhythmic efficacy, adverse effects, and predictive value of lidocaine testing.

Thirty patients received one of the lidocaine analogues--mexiletine or tocainide--orally for treatment of symptomatic ventricular arrhythmias. Crossover to the other analogue was allowed if initial drug treatment was unsuccessful, and the controlled use of other marketed oral antiarrhythmic agents was permitted. After follow-up of 7 +/- 3 months (SD), mexiletine was successful in 5 of 13 patients initially and in 5 of 14 patients who failed to respond to tocainide. Tocainide was successful in 1 of 17 patients initially and in 2 of 7 who did not respond to mexiletine. Combination therapy was used in nearly half of all ultimately successful drug trials. A common cause of drug trial failure for both drugs was the occurrence of adverse effects that frequently appeared well after hospital discharge. Response to lidocaine was a sensitive but nonspecific predictor of clinical outcome with mexiletine or tocainide that helped to identify drug-resistant patients. Finally, although mexiletine provided effective antiarrhythmic therapy more often than tocainide, response to one lidocaine analogue did not predict response to the other.

Adult↗

Predictive value of skin testing, neutrophil migration and C-reactive protein for postoperative infections in cardiopulmonary bypass patients.

Despite antibiotic cover for cardiac surgery the development of postoperative infection remains a feared complication. The present prospective study was designed to evaluate whether it is possible to identify preoperatively those individuals in whom the risk of a postoperative infection is significantly greater. Skin test response, chemotaxis and random migration of neutrophils, and serum levels of C-reactive protein (CRP) were chosen as indicators of host resistance. Pre-operatively and at defined postoperative time intervals, 80 patients undergoing open-heart surgery with the aid of cardiopulmonary bypass were examined. Of all the immunological variables measured in this study, the state of anergy proved the most reliable predictor of postoperative infection. Six of the nine pre-operatively anergic patients developed infections (P = 0.00026) representing one half of the postoperatively infected patients. No predictive role of CRP level or neutrophil chemotaxis can be derived from our data. The pre-operatively decreased random migration of polymorphonuclear leukocytes (PMN) from postoperatively infected patients, however, along with the significant defects in chemotactic and random PMN motility seen after cardiac surgery may partly explain the predisposition to bacterial infection in these patients. In conclusion, a pre-operative skin test makes a valuable contribution to the assessment of the patient's postoperative infectious risk.

Adult↗

Tuberculin skin test: estimation of positive and negative predictive values from routine data.

OBJECTIVE: To estimate, using routinely available data, the predictive values of tuberculin testing with 2TU RT23 for detection of latent tuberculosis infection (LTBI) in the Dutch population as a basis for recommendations on cut-off values at various levels of infection prevalence. DESIGN: Smoothed distributions of TST reactions among 312 tuberculosis patients and 2848 healthy non-BCG-vaccinated persons were used to estimate the sensitivity and specificity at various cut-off values. RESULTS: Sensitivity was 98.9% at 5 mm, 95.4% at 10 mm and 79.8% at 15 mm cut-off. Specificity with the corresponding cut-offs was 95.3%, 96.3% and 97.1% before and 98.0%, 98.8% and 99.6% after adjustment for presumed LTBI. At 10 mm, the positive predictive value (PPV) was > 75% if the infection prevalence in the tested population was at least 10%, but strongly declined with lower prevalences. For lower prevalences a cut-off of 15 mm was proposed, as this results in a higher PPV without greatly affecting the negative predictive value. CONCLUSION: Estimation of the predictive values of the TST from routine data can be useful for establishing cut-off values for detection of LTBI in different populations with different tuberculin preparations.

Adult↗

Cutaneous reactions to captopril. Predictive value of skin tests.

Cutaneous reactions associated with captopril treatment occurred in fifteen out of eighty-nine patients (17%). Dose reduction invariably led to improvement of the reaction but later recurrences were frequent (six patients). In four out of the fifteen patients captopril withdrawal ultimately was necessary. Skin tests and in vitro lymphocyte transformation tests with captopril were performed in these fifteen patients and also in nine captopril-treated control patients without adverse reactions. Positive epicutaneous skin tests were observed in five out of the fifteen patients including the four in whom captopril had to be withdrawn, but in none of the controls. Intracutaneous skin tests were positive in ten of the patients with cutaneous reactions and in two control patients. Captopril-induced in vitro lymphocyte transformation occurred in most patients with cutaneous reactions whereas in control patients captopril suppressed the in vitro lymphocyte proliferative response. Skin biopsies revealed histologic changes consistent with lymphocytic vasculitis. We conclude that epicutaneous skin tests with captopril are helpful in predicting the necessity of captopril withdrawal.

Adolescent↗

[Resistance testing in general practice--is it valid?].

Resistance of uropathogenic bacteria to antibiotics is an increasing problem in primary health care. The aim of this study was to evaluate antibacterial susceptibility testing of uropathogenic when performed in general practice. Urine specimens with a known quantity of typically uropathogenic bacteria were sent to 25 general practices. The predictive values of testing a bacterial strain as susceptible ranged from 0.89 (nitrofurantoin) to 1.00 (sulphamethizole), and the predictive value of testing a bacterial strain as resistant ranged from 0.55 (trimethoprim) to 0.90 (nitrofurantoin). If susceptibility testing is to be widely implemented in general practice it would be necessary to improve the validity.

Anti-Bacterial Agents↗

Validity of susceptibility testing of uropathogenic bacteria in general practice.

Resistance of uropathogenic bacteria to antibiotics is an increasing problem in primary health care. The aim of this study was to evaluate antibacterial susceptibility testing of uropathogenic bacteria when performed in general practice. Urine specimens with a known quantity of typically uropathogenic bacteria were sent to 25 general practices. The predictive values of testing a bacterial strain as susceptible ranged from 0.89 (nitrofurantoin) to 1.00 (sulphamethizole), and the predictive value of testing a bacterial strain as resistant ranged from 0.55 (trimethoprim) to 0.90 (nitrofurantoin). Interventions to improve the validity of susceptibility testing are desirable if the test should be incorporated in the diagnostic armamentarium in general practice.

Anti-Infective Agents, Urinary↗

[Anaphylaxis to muscle relaxants. Predictive value of intradermal tests and study of crossed anaphylaxis].

37 patients were studied, all of whom presented with anaphylaxis to a muscle relaxant. The diagnosis was made after simultaneous intradermal testing (IDT), human basophil degranulation tests (HBDT) and Prausnitz-Küstner tests (PK) of passive cutaneous anaphylaxis. Three tests were positive in 6 patients, both IDT and PK in 9, and both IDT and HBDT in 8. In 14 patients, the IDT, repeated twice, were positive both times. A search for crossed anaphylaxis to the other muscle relaxants was carried out in all the patients during a second series of tests, a few months to years after the first one. The drugs tested, at dilutions of the pharmaceutical preparation of 10(-3) or more, were: suxamethonium, gallamine, alcuronium, pancuronium, vecuronium, d-tubocurarine. The reliability of IDT in the diagnosis of anaphylaxis is discussed in terms of the small reactive concentration, the producibility of the tests, the one HBDT that did become positive later, and in one case the occurrence of shock by crossed anaphylaxis. Skin reactivity seemed to remain constant with time, so allowing the use of IDT as a diagnostic tool, in cases of old anaphylactoid shocks, occurring during general anaesthetics. The frequency of crossed anaphylaxis was assessed to be about 84%. The sensitivity to one or other drugs varied with each patient. Pancuronium and vecuronium appeared to be the least likely drugs to cause crossed anaphylaxis. The predictive use of these tests is discussed. It is also suggested that muscle relaxants with only one quaternary ammonium group should be used, this chemical characteristic probably reducing the risks of sensitization.

Adolescent↗

Factors affecting the predictive validity of the Braden Scale.

This descriptive correlational study explored the predictive validity of the Braden Scale and factors affecting it A Braden score was determined within 4 hours of admission for 50 adult medical/surgical inpatients. Independent skin assessments were made three times a week and at discharge. Fourteen patients (28%) developed pressure ulcers. A Braden score cutoff of 18 or less resulted in a 71% sensitivity, 83% specificity, 63% predictive value of a positive test, and 88% predictive value of a negative test. Three of the four patients incorrectly predicted to be not at risk scored "inadequate" on the nutrition subscale. Two of the four also were underweight. Of the six patients incorrectly predicted at risk for a pressure ulcer, three had been placed on air mattresses and were receiving levothyroxine (Synthroid). This study provides further evidence of the Braden Scale's predictive validity. The results suggest that patients who are underweight or getting inadequate nutrition be considered at increased risk for pressure ulcers.

Adult↗

Estimation of sensitivity, specificity and predictive values of two serologic tests for the detection of antibodies against Actinobacillus pleuropneumoniae serotype 2 in the absence of a reference test (gold standard).

Latent-class models were used to determine the sensitivity, specificity and predictive values of a polyclonal blocking enzyme-linked immunosorbent assay (ELISA) and a modified complement-fixation test (CFT) when there was no reference test. The tests were used for detection of antibodies against Actinobacillus pleuropneumoniae serotype 2 in a survey of respiratory diseases in Danish finishing pigs. The estimates were obtained by maximum-likelihood and also by a Bayesian method (implemented with Gibbs sampling). Possible dependence of diagnostic errors was investigated by comparing models where independence was assumed to models allowing for conditional dependence, given the true disease status. No strong evidence of conditional dependence in either test sensitivity or specificity was found. Assuming independence, maximum-likelihood estimates and 95% confidence intervals of the sensitivity and specificity of the ELISA were 100% and 92.8% (90.1-95.5%) and the corresponding values of the CFT were 90.6% (85.8-95.4%) and 98.6% (98.0-99.3%), respectively. Bayesian estimates and posterior 95% credible intervals of the sensitivity and specificity of the ELISA were 99.7% (98.7-100%) and 92.7% (89.9-95.3%) and of the CFT were 90.6% (86.0-95.3%) and 98.7% (98.0-99.3%). The sensitivity and specificity of a combined test, where the CFT is subsequently applied to the pig sera that test positive in the ELISA, were estimated at 90.2% (85.6-95.0%) and 99.9% (99.8-100%), respectively. The cost of the combined test was less than the cost of the use of the CFT alone, at prevalences <54%. Prevalences and predictive values and their 95% limits were estimated in six sub-samples of data. The estimates of sensitivity and specificity obtained in the present investigation generally validate those reported from other sources.

Actinobacillus Infections↗

[Prenatal determination of lung maturity from amniotic fluid--indications and new methods].

Although fetal lung maturity determination is carried out more and more rarely in the German-speaking area, a reliable information about the degree of lung maturity is still very important in the care of high-risk pregnancies. The side effects and costs of a postpartal surfactant administration can be avoided if lung maturity is proved. Indications for determination of fetal lung maturity are the threatening preterm delivery and the premature rupture of membranes before the 34th week of gestation and uncertain gestational age. Furthermore, in preeclampsia resp. in diabetes mellitus, which is difficult to control, premature delivery may be necessary. To improve lung maturity testing we introduce a new "sequence scheme" containing three lung maturity tests which are easy to carry out (in the following sequence: Amniostat-FLM ultrasensitive, counting of the lamellar bodies in amniotic fluid, surfactant/albumin ratio with TDx-FLM). The principle of this scheme is, that if any of these three tests indicates lung maturity, the sequence is terminated and no further test is performed. Only if all three tests indicated immaturity, the child was at risk for RDS. In 87 amniotic fluid samples with 7 RDS-cases, we achieved high predictive values for lung maturity (specificity 90%, sensitivity 100%, predictive value of positive test 47%, predictive value of negative test 100%). In 62% only one test was needed for lung maturity determination. It is possible to use other combinations in such a scheme (e.g. the L/S ratio). This might lead to equal or perhaps better results. An advantage of this suggested "sequence scheme" is that it can be performed in any clinic.

Amniocentesis↗