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At least 1,153 records · Page 64Linked to original sources
PubMed2000

Quantification of intracavitary brachytherapy parameters and correlation with outcome in patients with carcinoma of the cervix.

PURPOSE: To quantify the M. D. Anderson criteria for acceptable implant geometry; to relate our system of intracavitary radiotherapy (ICRT) prescription to Manchester and ICRU reference doses; and to correlate these parameters with outcome measures. METHODS AND MATERIALS: The relationships between intracavitary applicators and normal structures were measured directly from localization films of 808 applications performed in 396 patients who completed definitive treatment for cervical cancer between 1990 and 1994. The distances between applicators and tissue landmarks and the doses to Manchester and normal tissue reference points were correlated with outcome. RESULTS: The median distance from the tandem to the sacrum was 4.0 cm, or one-third the distance from the pubis to the sacrum. The mean distance between the vaginal ovoids and cervical marker seeds was 7 mm, and the median distance between the tandem and the posterior edge of the ovoids was 50% of the ovoid length. In 92% of insertions, vaginal packing was posterior to or within 5 mm of a line that passed through the posterior edge of the ovoids, parallel to the tandem. The median doses to Point A and rectal, bladder, and vaginal surface reference points were 87 Gy, 68 Gy, 70 Gy, and 125 Gy, respectively. Although these reference doses were not routinely used to prescribe treatment, consistent applicator geometry and source selection resulted in a relatively narrow range of delivered doses. The average ratios between the doses at bladder or rectal reference points and Point A were somewhat greater when smaller vaginal applicators were used. Patients received a median of 5600 mgRaEq-h from ICRT. The total mgRaEq-h were correlated with but were not proportional to the dose at Point A. There were no significant correlations between the doses to standard reference points and the rates of central recurrence or major complications. CONCLUSION: When ICRT implants are carefully placed, relatively high paracentral doses can be delivered that yield a high rate of central disease control with an acceptable rate of complications. The narrow range of doses delivered to standard reference points and their inconsistent correlation with the maximum doses delivered to normal tissues probably contributed to a lack of correlation between reference doses and outcome.

Adult↗
PubMed2002

Confusion assessment method in the diagnostics of delirium among aged hospital patients: would it serve better in screening than as a diagnostic instrument?

BACKGROUND: The Confusion Assessment Method (CAM) is an easy, four-step algorithmic diagnostic test developed to detect delirium. OBJECTIVE: To determine how sensitive and specific the CAM is in diagnosing delirium when compared with fully operationalized criteria of delirium according to the Diagnostic and Statistical Manual of Mental Disorders (DSM) editions III, III revised, and IV, and the International Classification of Diseases (ICD) 10th edition. METHODS: A cross-sectional study with blinded assessments was performed on consecutive elderly patients (>70 years) (n=81) in two acute geriatric hospitals in Helsinki, Finland. The sensitivity, specificity, likelihood ratios, and positive and negative predictive values of CAM were assessed with the DSM-III, DSM-III-R, DSM-IV, and ICD-10 criteria of delirium used as reference standards. RESULTS: Sensitivity rates of the CAM were proved to be only moderate (0.81-0.86) against all formal criteria of delirium. The specificity rates were lower (0.63-0.84), and far less than reported in previous studies using global assessment of the reference standard. Instead of the DSM-III-R, from which it is derived, the CAM seems more concordant with the DSM-IV criteria of delirium. The likelihood ratio for a positive CAM test was 5.06 and for a negative test 0.23, when compared with the DSM-IV. CONCLUSION: The CAM seems to be an acceptable screening instrument for delirium, but the diagnosis should be ensured according to the formal criteria of delirium, preferably by the DSM-IV.

Aged↗
PubMed2006

Simulation studies of the fidelity of biomolecular structure ensemble recreation.

We examine the ability of Bayesian methods to recreate structural ensembles for partially folded molecules from averaged data. Specifically we test the ability of various algorithms to recreate different transition state ensembles for folding proteins using a multiple replica simulation algorithm using input from "gold standard" reference ensembles that were first generated with a Go-like Hamiltonian having nonpairwise additive terms. A set of low resolution data, which function as the "experimental" phi values, were first constructed from this reference ensemble. The resulting phi values were then treated as one would treat laboratory experimental data and were used as input in the replica reconstruction algorithm. The resulting ensembles of structures obtained by the replica algorithm were compared to the gold standard reference ensemble, from which those "data" were, in fact, obtained. It is found that for a unimodal transition state ensemble with a low barrier, the multiple replica algorithm does recreate the reference ensemble fairly successfully when no experimental error is assumed. The Kolmogorov-Smirnov test as well as principal component analysis show that the overlap of the recovered and reference ensembles is significantly enhanced when multiple replicas are used. Reduction of the multiple replica ensembles by clustering successfully yields subensembles with close similarity to the reference ensembles. On the other hand, for a high barrier transition state with two distinct transition state ensembles, the single replica algorithm only samples a few structures of one of the reference ensemble basins. This is due to the fact that the phi values are intrinsically ensemble averaged quantities. The replica algorithm with multiple copies does sample both reference ensemble basins. In contrast to the single replica case, the multiple replicas are constrained to reproduce the average phi values, but allow fluctuations in phi for each individual copy. These fluctuations facilitate a more faithful sampling of the reference ensemble basins. Finally, we test how robustly the reconstruction algorithm can function by introducing errors in phi comparable in magnitude to those suggested by some authors. In this circumstance we observe that the chances of ensemble recovery with the replica algorithm are poor using a single replica, but are improved when multiple copies are used. A multimodal transition state ensemble, however, turns out to be more sensitive to large errors in phi (if appropriately gauged) and attempts at successful recreation of the reference ensemble with simple replica algorithms can fall short.

Algorithms↗
PubMedDate not supplied

Retention indices by wide-bore capillary gas chromatography with nitrogen-phosphorus detection.

The use of wide-bore capillary columns in gas chromatography (GC) with nitrogen-phosphorus detectors (NPD) is gaining popularity in the toxicology laboratory. Though the preferred method to achieve reproducible results and to make interlaboratory comparisons of GC data is by retention index (RI), the selectivity of the NPD has relegated its users to calculations of relative retention time. The present study utilizes a set of drugs as reference standards under temperature programmed conditions and presents a unique method of RI calculation. RI calculations are highly reproducible with this technique (day-to-day variations range from 0.3 to 3.4 RI units) and are comparable to packed column, FID generated reference data. A program, written in Basic, calculates RI values based on daily injections of the reference standards and searches a library of over 100 basic and acidic drugs.

Chromatography, Gas↗
PubMed1991

The biomechanical effects of deep tissue support as related to brow and facelift procedures.

The adverse effects of increased tension across a healing wound are well known. However, the effect of closing a wound in layers in order to decrease tension on the epidermis has been a source of controversy. It is hypothesized that deep tissue support decreases skin tension upon wound closure. In order to clarify this issue, a two-part study was designed to address the immediate effects of deep tissue support in vitro using fresh-frozen cadavers and in vivo on patients undergoing scheduled surgery. Closing skin tension was measured at standard reference points in coronal brow lift and rhytidectomy procedures performed with and without galeal closure and superficial musculoaponeurotic system (SMAS) procedures, respectively. Deep tissue support was found to significantly (p less than 0.05) decrease skin tension at the time of skin closure at standard reference points in coronal brow lift and rhytidectomy procedures performed on fresh-frozen cadavers. Similar significant (p less than 0.05) decreases in closing skin tension also were found in vivo in patients undergoing similar surgical procedures. Stress relaxation was not found to play a significant role in contributing to this immediate decrease in closing skin tension. It would appear, therefore, that deep tissue support, in the form of galeal closure and an SMAS procedure in coronal brow lift and rhytidectomy procedures, respectively, provides increased viscoelastic support, producing immediate significant decreases in closing skin tension in these procedures. The beneficial effects on wound healing, scar formation, tension-related trophic skin changes, and possible improved long-term results are discussed.

Adult↗
PubMed2005

Usefulness of myocardial parametric imaging to evaluate myocardial viability in experimental and in clinical studies.

OBJECTIVE: To evaluate whether myocardial parametric imaging (MPI) is superior to visual assessment for the evaluation of myocardial viability. METHODS AND RESULTS: Myocardial contrast echocardiography (MCE) was assessed in 11 pigs before, during, and after left anterior descending coronary artery occlusion and in 32 patients with ischaemic heart disease by using intravenous SonoVue administration. In experimental studies perfusion defect area assessment by MPI was compared with visually guided perfusion defect planimetry. Histological assessment of necrotic tissue was the standard reference. In clinical studies viability was assessed on a segmental level by (1) visual analysis of myocardial opacification; (2) quantitative estimation of myocardial blood flow in regions of interest; and (3) MPI. Functional recovery between three and six months after revascularisation was the standard reference. In experimental studies, compared with visually guided perfusion defect planimetry, planimetric assessment of infarct size by MPI correlated more significantly with histology (r2 = 0.92 versus r2 = 0.56) and had a lower intraobserver variability (4% v 15%, p < 0.05). In clinical studies, MPI had higher specificity (66% v 43%, p < 0.05) than visual MCE and good accuracy (81%) for viability detection. It was less time consuming (3.4 (1.6) v 9.2 (2.4) minutes per image, p < 0.05) than quantitative blood flow estimation by regions of interest and increased the agreement between observers interpreting myocardial perfusion (kappa = 0.87 v kappa = 0.75, p < 0.05). CONCLUSION: MPI is useful for the evaluation of myocardial viability both in animals and in patients. It is less time consuming than quantification analysis by regions of interest and less observer dependent than visual analysis. Thus, strategies incorporating this technique may be valuable for the evaluation of myocardial viability in clinical routine.

Aged↗
PubMedDate not supplied

Determination of mercury in carbon black by cold vapor atomic absorption spectrometry.

Recently, a new color additive, D&C Black No. 2, a high-purity furnace black in the general category of carbon blacks, was listed as a color subject to batch certification by the U.S. Food and Drug Administration. A simple procedure was developed to determine mercury (Hg) in D&C Black No. 2, which is limited by specification to not more than 1 ppm Hg. The method uses partial acid digestion followed by cold vapor atomic absorption and was developed by modifying a method used for other color additives. The carbon black samples are treated with a mixture of nitric and hydrochloric acids and heated by microwave in sealed Teflon vessels. The resulting solutions, which are stable to Hg loss for at least 1 week, are diluted and analyzed for Hg using cold vapor atomic absorption spectrometry. Validation was performed by spiking carbon black samples with inorganic Hg (HgNO3) at levels from 0.1 to 1.5 microg/g, and by analyzing 2 standard reference materials. At the specification level of 1 ppm Hg (1 microg Hg/g), the 95% confidence interval was +/-0.01 ppm Hg (0.01 microg Hg/g). The method developed in this study gave good results for very difficult-to-analyze materials, such as coal standard reference materials and carbon black. By eliminating volatility and adsorption factors through the formation of HgCl4(-2) complexes, one can avoid using extremely hazardous acids such as HF and HClO4.

Calibration↗
PubMed2004

Non-Hodgkin lymphoma and Hodgkin disease: coregistered FDG PET and CT at staging and restaging--do we need contrast-enhanced CT?

PURPOSE: To retrospectively compare diagnostic value of coregistered fluorine 18 fluorodeoxyglucose positron emission tomographic (PET) and computed tomographic (CT) scans obtained with low-dose nonenhanced CT (PET/CT) with those routinely obtained with contrast material-enhanced CT for staging and restaging of disease in patients with Hodgkin disease or high-grade non-Hodgkin lymphoma. MATERIALS AND METHODS: Sixty patients (mean age, 39.6 years +/- 17.1 [standard deviation]) with Hodgkin disease (n = 42) or high-grade non-Hodgkin lymphoma (n = 18) were included in this retrospective study. All patients underwent PET/CT and contrast-enhanced CT within a maximum of 24 days (mean, 9.1 days +/- 7.0) of each other for staging (n = 19) or first follow-up examination (n = 41). Findings were extracted from original written reports (PET/CT, contrast-enhanced CT) and compared with findings of reference standard, which included biopsy or follow-up with clinical, laboratory, or other imaging findings. For statistical analysis, sensitivity and specificity were calculated with findings of the reference standard. Agreement of both methods was determined with Cohen kappa and McNemar tests on a per-patient basis. RESULTS: For evaluation of lymph node involvement, sensitivity of PET/CT and contrast-enhanced CT was 94% and 88%, and specificity was 100% and 86%, respectively. For evaluation of organ involvement, sensitivity of PET/CT and contrast-enhanced CT was 88% and 50%, and specificity was 100% and 90%, respectively. Agreement of both methods was excellent (kappa = 0.84) for assignment of lymph node involvement but only fair (kappa = 0.50) for extranodal disease. A difference with P <.05 (McNemar test) was considered significant in regard to exclusion of disease with PET/CT, compared with contrast-enhanced CT. CONCLUSION: PET/CT performed with nonenhanced CT is more sensitive and specific than is contrast-enhanced CT for evaluation of lymph node and organ involvement, especially regarding exclusion of disease, in patients with Hodgkin disease and high-grade non-Hodgkin lymphoma.

Adolescent↗
PubMed2003

Hematologic and biochemical laboratory parameters before and after a marathon race.

Marathon racing is a strenuous exercise that has a profound effect on many laboratory parameters. Participants in marathon races may require abstinence of exercise and the performance of laboratory assays several days after the event. The aim of this study was to evaluate the possible changes in blood cell count and biochemical parameters observed in participants in a marathon 3 days before and 3 days after and before and immediately after a cardiopulmonary exercise test. Incremental cycle ergometry up to maximal capacity was performed in 7 marathon runners, 3 days before and 3 days after the race. The % peak oxygen consumption (peak %VO(2)) achieved was statistically significantly lower after than before the race ( p = 0.02). No statistically significant differences were observed in cardiac frequency ( p = 0.148) or blood cell count ( p = 0.501). Also, the concentration of sodium, potassium, calcium, magnesium, lactate dehydrogenase (LDH), phosphocreatine kinase (CPK) and glucose, measured before and immediately after the pulmonary exercise test, did not differ significantly ( p < 0.5). A significant percentage of the laboratory results were outside the standard reference rates. According to our data, exercise performance, as expressed by peak %VO(2), continued to be decreased in marathon runners 3 days after the race. The blood cell count and biochemical parameters did not differ significantly but many marathon runners were outside the standard reference rates. Unfortunately, only 7 subjects were available for this study. Further studies with larger samples and with samples obtained at multiple times during and after exercise are needed to clarify the effects of long-distance running.

Blood Cell Count↗
PubMed1996

Sputum gram's stain in community-acquired pneumococcal pneumonia. A meta-analysis.

The usefulness of the sputum Gram's stain is controversial. This meta-analysis was designed to evaluate the sensitivity and specificity of the sputum Gram's stain in community-acquired pneumococcal pneumonia. Using a predetermined protocol, articles were discovered through a MEDLINE search (1966 to 1993) and the examination of bibliographies and were graded for quality by three blinded reviewers. Information on the reference standard, blinding, stain interpreter, control for antibiotic use, and definition of a positive test was collected. We found 12 articles containing 17 test characteristics to evaluate. The number of patients in each study ranged from 16 to 404. Sputum culture was the most common reference standard (10 of 17 estimations). Sensitivity ranged from 15% to 100% and specificity from 11% to 100%. Test characteristics varied markedly among studies and appeared related partly to the test interpreter. The sputum Gram's stain may yield misleading results in community-acquired pneumonia, as its sensitivity and specificity vary substantially in different settings. A practitioner electing to use the study should be well trained and use a specific definition for a positive test.

Community-Acquired Infections↗
PubMed2004

[Trial therapy with proton pump inhibitors is not a suitable test for gastroesophageal reflux disease; a meta-analysis of the diagnostic test characteristics].

OBJECTIVE: To determine the value of successful trial therapy with proton-pump inhibitors (PPIs) as a diagnostic test for gastro-oesophageal reflux disease (GERD). DESIGN: Systematic review and meta-analysis. METHOD: Studies were included in which the clinical response to a short course (1-4 weeks) of PPI therapy could be related to abnormal results of 24-hr pH monitoring, gastroscopy, and/or diagnostic questionnaires. The sensitivity and specificity of the trial therapy were calculated. The ROC method was used to summarize the test characteristics across studies. RESULTS: With 24-hr pH monitoring as the reference standard, the positive likelihood ratio of the diagnosis 'reflux disease' ranged from 1.63 to 1.87 and the combined estimates of sensitivity and specificity in the various studies were 0.78 (95% CI: 0.66-0.86) and 0.54 (0.44-0.65), respectively. These values were lower with the other reference standards. CONCLUSION: Although there were insufficient data to determine the effect of varying dosages of PPIs and duration of therapy on the test characteristics, successful short-term treatment with PPIs in patients suspected of having GERD provides insufficient certainty as to the diagnosis.

Dose-Response Relationship, Drug↗
PubMed2005

Clinical validation of the NeuroScreen.

The NeuroScreen comprises two easily administered components: the Brief NeuroCognitive Screen (BNCS), designed to estimate the frequency of human immunodeficiency virus (HIV)-associated cognitive disorders; and the Brief Peripheral Neuropathy Screen (BPNS), for distal sensory polyneuropathy (DSPN) in HIV. In this study, both the NeuroScreen and a more extensive standardized validation neurodiagnostic evaluation were administered to HIV-positive subjects (N = 301) enrolled in two large cohort studies at multiple sites. BNCS performance was summarized in the form of a demographically adjusted mean z-score, the NPZ3. The area under the receiver-operating characteristic (ROC) curve for the BNCS as compared to the reference standard neuropsychological (NP) evaluation was 0.74 (95% confidence interval [CI] 0.69, 0.79). Using a cut-point of -0.33 on the NPZ3 provided a correct classification rate of 68%, with roughly balanced sensitivity (65%) and specificity (72%). Under the assumption of a 30% prevalence of cognitive impairment, the calculated positive predictive value (PPV) of the BNCS was 86%. Relative to its reference standard, a modified Total Neuropathy Score (TNS) administered by a neurologist, the BPNS gave a similar correct diagnostic classification rate of 78%; sensitivity 49% [95%, 60%]; specificity 88% [95% Cl82%, 91%]. Under the assumption of a 40% prevalence of DSPN, the PPV of the BPNS was 72%. These predictive values suggest that the NeuroScreen will be useful for tracking trends in the prevalence of HIV-associated neurologic disease in large cohorts in the era of combination antiretroviral therapy. However, because it yields substantial numbers of false positives and negatives, the NeuroScreen may be less useful in evaluating individual patients.

AIDS Dementia Complex↗
PubMed1983

Cytotoxicity of a short-fiber chrysotile asbestos for human alveolar macrophages: preliminary observations.

Studies were performed to compare the cytotoxicity for human alveolar macrophages of a naturally occurring short-fiber chrysotile asbestos (RG 144) to that of a standard reference mixed-fiber (long and short) chrysotile asbestos (UICC chrysotile A. Rhodesian). Parallel studies were also performed with quartz (Min-U-Sil 15), a known macrophage toxin. On a mass basis, and after 24 hr incubation, RG 144 was more cytotoxic than the UICC standard reference fiber and less toxic than quartz (silica). The cytotoxic potential of RG 144 chrysotile was further enhanced after size reduction by milling. These findings may have important biologic implications with respect to the use of short-fiber asbestos in industry.

Adult↗
PubMed2002

Helical CT versus EUS with fine needle aspiration for celiac nodal assessment in patients with esophageal cancer.

BACKGROUND: Conventional CT is insensitive for detection of metastatic involvement of celiac lymph nodes in esophageal cancer. Helical CT has theoretical advantages over "slice" CT in this regard, but its performance has not yet been prospectively studied. METHODS: Consecutive patients with untreated esophageal cancer were recruited after obtaining informed consent. Helical CT was performed on all patients and TNM staging was performed by a single radiologist. Subsequently, all patients underwent esophageal radial and, as needed, curvilinear array EUS with fine needle aspiration (FNA), for evaluation of celiac lymph nodes and TNM staging. Test performance characteristics with 95% confidence intervals were calculated, assuming EUS with FNA as the reference standard. RESULTS: Forty-eight patients were recruited, of whom 37 (77%) were men. The mean (SD) age was 63.6 (10) years. Excluding 5 patients in whom a confirmatory FNA was not available (n = 43), helical CT identified celiac lymph nodes in 12 (28%) patients. The reference standard of EUS with FNA identified 15 (35%) patients with metastatic celiac lymph nodes, giving a sensitivity, specificity, and positive and negative predictive values for helical CT of 53% (95% CI [28%, 79%]), 86% (95% CI [73%, 99%]), 67% (95% CI [40%, 93%]), and 77% (95% CI [63%, 92%]), respectively, for assessing celiac lymph nodal involvement. The sensitivity and specificity of helical CT in detecting T4 disease were 25% (95% CI [3.8%, 46%]) and 94% (95% CI [85%, 100%]), respectively. There were 12 patients (25%; 95% CI [13%, 37%]) who were felt to have resectable disease by helical CT but had either metastatic involvement of celiac lymph nodes or T4 disease by EUS/FNA. CONCLUSIONS: Despite technological advances, helical CT still appears unreliable, mainly because of insensitivity, for the identification of inoperable T4 or metastatic involvement of celiac lymph node disease in esophageal cancer.

Adenocarcinoma↗
PubMed2006

Purchasing online journal access for a hospital medical library: how to identify value in commercially available products.

BACKGROUND: Medical practice today requires evaluating large amounts of information which should be available at all times. This information is found most easily in a digital form. Some information has already been evaluated for validity (evidence based medicine sources) and some is in unevaluated form (paper and online journals). In order to improve access to digital information, the School of Clinical Medicine and Research at the University of the West Indies and Queen Elizabeth Hospital decided to enhance the library by offering online full text medical articles and evidence based medicine sources. The aim of this paper is to evaluate the relative value of online journal commercial products available for a small hospital and medical school library. METHODS: Three reference standards were chosen to represent the ideal list of core periodicals for a broad range of medical care: 2 Brandon/Hill selected lists of journals for the small medical library (BH and BH core) and the academic medical library core journal collection chosen for the Florida State University College of Medicine Medical Library. Six commercially available collections were compared to the reference standards and to the current paper journal subscription list as regards to number of journals matched and cost per journal matched. Ease of use and presence of secondary sources were also considered. RESULTS: The cost per journal matched ranged from US $3194 to $81. Because of their low subscription prices, the Biomedical Reference Collection and Proquest products were the most cost beneficial. However, they provided low coverage of the ideal lists (12-17% and 21-32% respectively) and contained significant embargoes on current editions, were not user friendly and contained no secondary sources. The Ovid Brandon/Hill Plus Collection overcame these difficulties but had a much higher cost-benefit range while providing higher coverage of the ideal lists (14-47%). CONCLUSION: After considering costs, benefits, ease of use, embargoes, presence of secondary sources (ACP Journal Club, DARE), the Ovid Brandon/Hill Plus Collection was the best choice for our hospital considering our budget. However, the option to individually select our own journal list from Ovid and pay per journal has a certain appeal as well.

Journal Article↗
PubMed1984

Standard electromotive force of the H2-AgCl;Ag cell in 30, 40, and 50 mass% dimethyl sulfoxide/water from -20 to 25 degrees C: pK2 and pH values for a standard "Bicine" buffer solution at subzero temperatures.

The establishment of the pH (designated pH*) of a standard buffer solution suitable as a pH reference in 30, 40, and 50 mass% dimethyl sulfoxide (DMSO)/H2O mixtures at temperatures in the range -20 to 0 degrees C is reported. The buffer material selected was the ampholyte Bicine (N,N-bis(2-hydroxyethyl)glycine), and the reference standard consists of equal molal quantities of Bicine and its sodium salt. The assignment of pH* values rests on measurements of the emf of cells without liquid junction, Pt;H2(g, 1 atm) [Bicine, Na Bicinate, NaCl [AgCl;Ag, and the pH* was derived from a determination of K2, the equilibrium constant for the dissociation process (Bicine) +/- in equilibrium (Bicinate)- + H+. The standard emf in the DMSO/H2O solvents at subzero temperatures was determined from emf measurements of the cell with solutions of HCl replacing the buffer-chloride mixture.

Buffers↗
PubMed2007

Evaluation of a Digene-recommended algorithm for human papillomavirus low-positive results present in a "retest zone".

The Digene Hybrid Capture 2 (hc2) high-risk human papillomavirus (HPV) DNA test (Digene, Gaithersburg, MD) is widely used for triage of women with atypical squamous cells of undetermined significance. Results in a "retest zone" (weakly positive tests) are repeated up to 2 times according to the Digene-recommended algorithm. We studied 56 cervical samples in the retest zone. Specimens were tested by a multiplex polymerase chain reaction (PCR)-based genotyping assay, and relevant cytopathologic results were reviewed. Digene results were compared with a reference standard that combined PCR genotyping and cytopathology results. The first repeated Digene assay yielded a sensitivity of 85.2% and a specificity of 62.1% with false-positive and false-negative rates of 40.0% and 15.4%, respectively. The 22 negative samples underwent a second retest and 18 (82%) were negative by the reference standard. The combined first and second retest sensitivity, specificity, and predictive values remained unchanged from the first retest alone. Repeating specimens in the retest zone is necessary, but a second retest does not offer advantages over the first retest.

Algorithms↗
PubMed2003

Are diagnostic lumbar medial branch blocks valid? Results of 2-year follow-up.

The precise cause of low back pain based on clinical history, physical examination, radiological imaging, and electrophysiological testing can be identified in only 15% of patients in the absence of disc herniation and neurological deficit. The prevalence of chronic lumbar zygapophysial (facet) joint pain ranges from 15% to 45% utilizing comparative local anesthetic blocks in controlled settings in accordance with the criteria established by the International Association for the Study of Pain. Currently, facet joint injection procedures are considered as the gold standard in the diagnosis of facet joint pain. Facet blocks have been criticized as lacking diagnostic validity, along with other tests, including discography, neurophysiologic tests, stress radiographs, x-ray studies, bone scintigraphy, thermography and diagnostic ultrasound. However, these assumptions have been based on biased evaluations without consideration of the criteria of the International Association for the Study of Pain, as well as the nature of controlled diagnostic blocks. Utilizing the criteria established by the Agency for Healthcare Research and Quality (AHRQ) for Systems to Rate the Strength of Scientific Evidence, it was shown that the validity, specificity, and sensitivity of facet joint nerve blocks are considered strong in the diagnosis of facet joint pain. The accuracy of a diagnostic test is best determined by comparing it to an appropriate reference standard, such as biopsy, surgery, autopsy or long-term follow-up. Since we are unable to apply reference standards of biopsy, surgery, or autopsy, and pain relief has been argued as an inconsistent feature, long-term follow-up has been considered as the best indicator. This study was undertaken to evaluate stability of the diagnosis of lumbar facet joint pain following comparative local anesthetic blocks at a follow-up after 2 years. The results showed that 85% of the patients available for follow-up withstood the diagnosis of facet joint pain at the end of 2 years, whereas this proportion decreased to 75%, if all the patients in the study were included in the analysis.

Journal Article↗