Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Sampling Errors”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 973 records · Page 54Linked to original sources
PubMed2000

Helicobacter pylori gastritis of the gastric carcinoma phenotype: is histology capable of identifying high-risk gastritis?

Several studies have shown that Helicobacter pylori infection implies an increased risk for developing gastric carcinoma. However, it has to be considered that only a few among those infected with H. pylori develop gastric cancer. It is therefore desirable to identify risk indicators of H. pylori gastritis in the presence of which gastric carcinoma is most likely to occur. In our view, the risk indicators intestinal metaplasia and atrophy, frequently cited in the literature, are not suitable, as they are focal changes whose detection at the routine diagnostic workup may be confounded by sampling error and because early carcinoma (in particular of the diffuse type) is often not associated with intestinal metaplasia or atrophy. For this reason we investigated the diffuse gastritis parameters "grade of gastritis" and "activity of gastritis" for their suitability as risk indicators. We found that H. pylori gastritis, particularly in the corpus, is significantly more pronounced in gastric carcinoma patients or individuals with a family history of gastric cancer than in matched controls. Hence, a simple comparison of the grade of gastritis and activity of gastritis in the antrum and corpus might help identify patients with H. pylori gastritis with an increased cancer risk. Currently. we are testing this hypothesis in an ongoing gastric cancer prevention study in Germany, Austria, and Czechia.

Cell Transformation, Neoplastic↗
PubMed2000

Pathological aspects of brain tumors.

Brain tumors based on their histogenesis, consist of all tumors, derive from the entirely tissue in the intracranial space, both from the neuro-ectodermal/neuro-epithelial tissue and the mesenchymal tissue. By their location they can be divided into infratentorial or supratentorial, and further into deep vs. superficial. The interesting and unique, there are age distribution or location-sex specificity of some brain tumors (BT). WHO Histopathological Typing of Tumors by the CNS, also showing progress on both of their members and new special types of some BT, especially for the meningiomas and neuro-epithelial/neuroglial type. Periodic investigations by the Department of Anatomic Pathology, the Faculty of Medicine, University of Indonesia did not show major changes in their BT types, but there was on their tumors ranging. Astrocytoma (including glioblastoma multiforma) for a while was replaced by meningioma as the most common CNS/Intracranial tumor. There are some techniques for the handling of CNS specimens depending on further purposes through on biomolecular activities or defects. The routine technique using light microscope examination was the most useful one for daily diagnosis for many years. Some immunohistochemistry techniques are needed for difficult cases, e.g., GFAP, NE 14, NSE, S100, and MBP. Diagnostic problems could be caused by tissue- or cell-sampling errors, which are influenced by the tumor location itself. Thus, neurosurgeons encounter problems to pick biopsy intraoperative, or by mishandling by the laboratory of anatomic pathology. Formerly, as final diagnosis, grading of CNS tumors must be put according to the Clinical interest for further management of the patient. CNS grading ranges from grade I (benign looking) to IV (malignant). Morphological grading is based on Kernohan and Adson (1949), or Kernohan and Sayre (1952).

Astrocytoma↗
PubMed2000

3-D computer visualization and interactive prostate biopsy simulation leads to an improved systematic technique for the detection of prostate cancer: clinical correlation.

OBJECTIVES: Urologists routinely use the systematic sextant needle biopsy technique to detect prostate cancer. However, recent evidence suggests that this technique has a significant sampling error. Recent data based upon whole-mounted step-sectioned radical prostatectomy specimens using a 3-D computer assisted prostate biopsy simulator suggests that an increased detection rate is possible using laterally placed biopsies. A new 10-core biopsy pattern was shown to be superior to the traditional sextant biopsy. This pattern includes the traditional sextant biopsy cores and four laterally placed biopsies in the right and left apex and mid portion of the prostate gland. The objective of this study is to confirm the higher prostate cancer detection rate obtained using the 10-core biopsy pattern in a small cohort of patients. METHODS: We retrospectively reviewed 35 consecutive patients with a pathologic diagnosis of prostate cancer biopsied by a single urologist using the 10-core biopsy pattern. The frequency of positive biopsy was determined for each core. Additionally, the sextant and 10-core prostate biopsy patterns were compared with respect to prostate cancer detection rate. RESULTS: Of the 35 patients diagnosed with prostate cancer, 54.3% (19/35) were diagnosed when reviewing the sextant biopsy data only. Review of the 10-core pattern revealed that an additional 45.7% (16/35) of patients were diagnosed solely with the laterally placed biopsies. The laterally placed biopsies had the highest frequency of positive biopsies when compared to the sextant cores. CONCLUSIONS: Our results suggest that biopsy protocols that use laterally placed biopsies based upon a five region anatomical model are superior to the routinely used sextant prostate biopsy pattern. Lateral biopsies in the apex and mid portion of the gland are the most important.

Biopsy, Needle↗
PubMed2000

[Quantification of iron overload].

Iron overload involves primarily hepatocytes in case of digestive hyperabsorption (hemochromatosis and dyserythropoiesis) and macrophages in case of transfusional excess. Serum iron and transferrin saturation are poorly correlated with the degree of iron overload. Serum ferritin is a better reflect of iron stores but numerous clinical conditions, unrelated to variations of iron load, can increase the serum level. Biochemical determination of liver iron overload is the gold standard of iron quantification and well correlated to the level of iron burden appreciated by the amount of iron removed by venesection, but its determination necessitates a liver biopsy and is dependant of sampling error in case of heterogeneous iron deposits (cirrhosis). The sensitivity of computed tomography is insufficient, beeing unable to detect iron overload below 5 times the normal liver iron load, especially in case of associated steatosis. Magnetic resonance imaging is a valuable tool when using T2 weighted gradient echo sequences on 1.5 Tesla magnet and permits non invasive iron overload quantification.

Biopsy↗
PubMed2000

Parietal lobe epilepsy.

When symptoms such as lateralized paresthesias or pain occur prominently and early in partial seizures, parietal lobe seizure origin should be suspected. Most patients with parietal lobe seizures, however, have no symptoms or signs suggesting the parietal lobe. In the absence of detectable epileptogenic lesions, these patients without clinical seizure characteristics suggesting parietal lobe origin can present with misleading findings, resulting in erroneous localization, which can, in turn, lead to ineffective surgical intervention (23,25). Although ictal SPECT might provide vital evidence of parietal lobe seizure origin (25), as noted previously, this technology also can produce misleading data in some patients (52). Even when parietal lobe seizure origin is suspected, in the absence of a structural lesion, documenting this with invasive monitoring can be difficult. The parietal lobes, like the frontal lobes, are large, diffuse structures, and the potential for sampling error is high (19). Spread patterns are unpredictable and can result in false localization (23). Even with extensive and repetitive invasive studies, localization can prove elusive (53). No well-documented series of patients with non-lesional parietal lobe epilepsy in the modern literature who have been cured by surgery have been reported as a result of a combination of the rarity of the condition, the lack of correct recognition, as well as the difficulty of localization. Patients with medically intractable parietal lobe seizures, however, can experience excellent surgical results (23,24). Postoperative parietal lobe symptoms and signs, even when extreme, are usually not enduring (patient 3). One of our patients, however, did develop a chronic pain syndrome (48).

Epilepsy↗
PubMed2000

Transbronchial needle aspiration: guidance with CT fluoroscopy.

BACKGROUND: Bronchoscopy with transbronchial needle aspiration (TBNA) is valuable to diagnose lesions in the mediastinum and lung, but conventional fluoroscopic guidance may be suboptimal. We describe the use of CT fluoroscopy to provide real-time, transaxial TBNA localization, thus facilitating biopsy. METHODS: Patients were selected because of prior unsuccessful bronchoscopy or anticipated difficulty owing to small size or inaccessibility of the lesion. CT fluoroscopy consists of a spiral CT scanner adapted using a rapid-reconstruction algorithm and hardware that permits real-time in-room imaging. The bronchoscope was inserted on the CT scanner, which was used to guide TBNA instruments into the target lesion. RESULTS: Of 27 patients who underwent TBNA with CT fluoroscopic assistance, 15 had mediastinal nodes, and 12 had lung nodules or focal infiltrates. Mean lesion size was 1.7 cm in the mediastinum, 2. 2 cm in the lung. A correct diagnosis was established in 10 of 12 mediastinal lesions (83%) for which follow-up was available and in 8 lung lesions (67%). Diagnoses included small cell and non-small cell lung cancer and invasive aspergillosis. False-negative results were caused by sampling errors or inability to reach the lesion as documented by CT fluoroscopy. Postprocedure CT fluoroscopy revealed no complications. CONCLUSION: CT fluoroscopy provides effective, real-time guidance for TBNA and may be particularly valuable in patients with small or less accessible mediastinal or lung lesions.

Adult↗
PubMed2000

Do children with Hodgkin's disease have a better prognosis than adults? Application of a generalised linear model to a systematic review of published results.

This investigation aimed to compare survival rates in paediatric and adult Hodgkin's disease using published results. When comparing results obtained in different studies and institutions it is important to explain, estimate and allow for heterogeneity between studies. This was attempted though systematic inclusion of a large number of published results, through modelling the influence of covariates on survival using a generalised linear model, and by estimation of both the sampling errors in the extracted survival rates and the heterogeneity between studies. A significant superiority of treatment results in paediatric institutions compared with adult institutions was demonstrated, allowing for differences in patient and treatment characteristics.

Adult↗
PubMed2001

[Diagnostic laparoscopy--a useful tool in abdominal lymphoma].

Imaging-guided (CT/US) percutaneous biopsy has significantly improved diagnosis of intra-abdominal lymphoma. However, in many cases the tissue retrieved may be inadequate for specialized studies such as immunophenotyping or cytogenetic analysis that may be required for a complete analysis of lymphoma or determination of therapy. The success of diagnostic laparoscopy in the diagnosis and staging of gastrointestinal malignancies suggests that it could be used for intra-abdominal lymphomas as well. We describe our experience in 15 patients with suspected lymphoma who underwent diagnostic laparoscopy during 1995-98. Preoperative investigation performed in all included percutaneous FNA in 9 without conclusive diagnosis. Laparoscopy was diagnostic for lymphoma in 14 (93%) while in 1 there was a false negative result due to sampling error and the lymphoma was only diagnosed at a second laparoscopy. There was no mortality nor any major complication. Average hospital stay was 2 days and patients were then referred for further oncological treatment. Our experience shows that diagnostic laparoscopy is a safe and efficient tool and without major complications in diagnosing abdominal lymphoma.

Abdominal Neoplasms↗
PubMed1975

Chronic persistent hepatitis. A clinical, serological, and prognostic study.

The diagnosis of chronic persistent hepatitis is based on a combination of clinical and morphological data. During a 7-year period 26 cases were diagnosed in 3 medical departments in Copenhagen. In 22 patients the disease was considered to be a sequela to acute viral hepatitis, and 12 had Australia antigen in serum. Only few patients had circulating auto-antibodies. The clinical and biochemical activity at the time of diagnosis was usually slight. A morphological and clinical follow-up study revealed that the course of the disease was generally benign. However, in 3 patients the last repeat biopsy showed progression to cirrhosis, severe portal fibrosis, and chronic aggressive hepatitis. Such exceptions may represent a sampling error in the interpretation of the first needle biopsy, or the correct diagnosis may have been chronic aggressive (active) hepatitis at a stage with slight activity. Clinical and biochemical observation is recommended in chronic persistent hepatitis, and in some patients serial needle biopsies are necessary to reveal the few exceptional cases which progress to an active chronic liver disease.

Adolescent↗
PubMed2001

The interaction of asbestos and smoking in lung cancer.

Both cigarette smoke and inhaled asbestos fibres can cause lung cancer, but the assessment of how these agents act in combination is a matter of great difficulty. In non-smokers, the condition is so rare that, in any cohort of asbestos workers, the standardised mortality ratio (SMR, that is the ratio of the numbers of deaths observed and expected) is quite imprecise. The SMR for smokers, with which it has to be compared, is also subject to sampling error, making the interaction even more unstable. This accounts for much of the variation that has bedevilled evaluation. The debate has been concentrated on two hypotheses: additive (asbestos and cigarette smoke act independently) and multiplicative (asbestos produces an effect proportional to the effect of smoking). The very few data available until 1977 failed to fit the former and fitted the latter only poorly. They would have fitted better a hypothesis of greater synergism, but the only one proposed was too convoluted. So the multiplicative model appeared the only alternative, and was deemed 'accepted'. The ratio of lung cancer SMRs for non-smokers and smokers was generalised into the relative asbestos effect, RAE, with all the advantages of a parametric statistic (Berry et al., 1985, British Journal of Industrial Medicine 42, 12). On the multiplicative hypothesis, RAE=1, while RAE>1 indicates less synergism. The RAEs for the three most recent of the six results then available were >1; for one, P<0.005. From the six results combined, it was concluded that 'overall non-smokers have a relative risk of lung cancer due to asbestos that is 1.8 times that of smokers'. Some admitted uncertainty about the figure 1.8 was seized upon and even the thrust of the conclusion has been very largely disregarded. So too has the RAE and all its benefits. As a result, all later reviewers have been led into error, much of it serious: in particular, they have failed to appreciate how much of the variation arises from the inevitable imprecision of all RAEs. This failure led reviewers in 1994 to discard, quite without justification, those interactions which were less than multiplicative and came from cohort studies. Although case-referent studies seemed to support the multiplicative hypothesis, the information from them is essentially unreliable. Thus it cannot weaken the conclusions from the cohort studies, that the multiplicative hypothesis is untenable and that the relative risk of lung cancer from asbestos exposure is about twice as high in non-smokers as in smokers; the best estimate of RAE is 2.04, with 95% confidence interval 1.28-3.25. This finding is not only of high statistical significance but of great social and scientific importance.

Asbestos↗
PubMed2001

Radioguided sentinel lymph node biopsy in breast cancer surgery.

The concept of sentinel lymph node biopsy in breast cancer surgery relates to the fact that the tumor drains in a logical way through the lymphatic system, from the first to upper levels. Therefore, the first lymph node met (the sentinel node) will most likely be the first to be affected by metastasis, and a negative sentinel node makes it highly unlikely that other nodes are affected. Because axillary node dissection does not improve prognosis of patients with breast cancer (being important only to stage the axilla), sentinel lymph node biopsy might replace complete axillary dissection to stage the axilla in clinically N0 patients. Sentinel lymph node biopsy would represent a significant advantage as a minimally invasive procedure, considering that, after surgery, about 70% of patients are found to be free from metastatic disease, yet axillary node dissection can lead to significant morbidity. Furthermore, histologic sampling errors can be reduced if a single (sentinel) node is assessed extensively rather than few histologic sections in a high number of lymph nodes per patient. Although the pattern of lymph drainage from breast cancer can be variable, the mammary gland and the overlying skin can be considered as a biologic unit in which lymphatics tend to follow the vasculature. Therefore, considering that tumor lymphatics are disorganized and relatively ineffective, subdermal and peritumoral injection of small aliquots of radiotracer is preferred to intratumoral administration. (99m)Tc-labeled colloids with most of the particles in the 100- to 200-nm size range would be ideal for radioguided sentinel node biopsy in breast cancer. Lymphoscintigraphy is an essential part of radioguided sentinel lymph node biopsy because images are used to direct the surgeon to the site of the node. The sentinel lymph node should have a significantly higher count than that of background (at least 10:1 intraoperatively). After removal of the sentinel node, the axilla must be reexamined to ensure that all radioactive sites are identified and removed for analysis. The sentinel lymph node should be processed for intraoperative frozen section examination in its entirety, based on conventional histopathology and, when needed, immune staining with anticytokeratin antibody. The success rate of radioguidance in localizing the sentinel lymph node in breast cancer surgery is about 94%--97% in institutions where a high number of procedures are performed and approaches 99% when combined with the vital blue dye technique. At present, there is no definite evidence that negative sentinel lymph node biopsy is invariably correlated with negative axillary status, except perhaps for T1a-b breast cancers, with a size of < or =1 cm. Randomized clinical trials should elucidate the impact of avoiding axillary node dissection on patients with a negative sentinel lymph node on the long-term clinical outcome of patients.

Breast Neoplasms↗
PubMed2001

[Efficacy of the urine antibody test for detection of Helicobacter pylori: comparison with serum antibody tests].

A urine-based enzyme-linked immunosorbent assay kit (URINELISA) for detection of the antibody for H. pylori has recently been developed. We evaluated the diagnostic capability of the URINELISA test in comparison with two serum IgG antibody kits (HM-CAP and Helico G) for H. pylori infection. The subjects of this study were 173 patients. H. pylori was detected by means of culture, immunohistochemical staining and rapid urease test of endoscopically obtained biopsy specimens. A positive diagnosis of H. pylori was when at least one of three tests was positive and a negative diagnosis when all three were diagnosed as H. pylori positive and 23 as negative. We also examined the diagnostic potential of the antibodies in urine and in serum by using the results of the bioptic methods as the gold standard. The sensitivity of both URINELISA and HM-CAP was 93.3% and that of Helico G 94.7%, while their respective specificities were 47.8%, 65.2% and 52.2%. The URINELISA kit thus showed high sensitivity but relatively low specificity. The latter was due to sampling errors in the bioptic procedure because the subjects of this study included many elderly patients with atrophic gastritis. The level of the antibody in urine decreased markedly after 2 months of eradication therapy. We conclude that the URINELISA kit is as effective as serum antibody kits for the diagnosis of H. pylori infection.

Adolescent↗
PubMed2001

[Lymphoepithelial cyst of the pancreas].

Authors present a case of a retroperitoneal lymphoepithelial cyst, which occurs rarely in this localisation. The histological picture is reminiscent of a branchiogen cyst. Usually it is recognised accidentally, with US or CT examinations performed for other reasons. In case the general condition of the patient is satisfactory, the surgical removal of such a tumour is recommended, since it is almost impossible to differentiate from more harmful lesions by CT or US examination, and if there are no tumour cells on the smears obtained by fine needle aspiration, there is always the doubt of sampling error.

Aged↗
PubMed2001

Using jugular venous catheters in patients with traumatic brain injury.

Sjo2 monitoring has several important limitations, such as catheter reliability, sampling error, and lack of regional specificity. However, combining Sjo2 monitoring with other available technologies can facilitate optimization of treatment and improve outcomes in patients with severe brain injuries.

Algorithms↗
PubMed2001

The role of method in treatment effectiveness research: evidence from meta-analysis.

A synthesis of 319 meta-analyses of psychological, behavioral, and educational treatment research was conducted to assess the influence of study method on observed effect sizes relative to that of substantive features of the interventions. An index was used to estimate the proportion of effect size variance associated with various study features. Study methods accounted for nearly as much variability in study outcomes as characteristics of the interventions. Type of research design and operationalization of the dependent variable were the method features associated with the largest proportion of variance. The variance as a result of sampling error was about as large as that associated with the features of the interventions studied. These results underscore the difficulty of detecting treatment outcomes, the importance of cautiously interpreting findings from a single study, and the importance of meta-analysis in summarizing results across studies.

Behavior Therapy↗
PubMed2002

Radioguided sentinel lymph node biopsy in malignant cutaneous melanoma.

The procedure of sentinel lymph node biopsy in patients with malignant cutaneous melanoma has evolved from the notion that the tumor drains in a logical way through the lymphatic system, from the first to subsequent levels. As a consequence, the first lymph node encountered (the sentinel node) will most likely be the first affected by metastasis; therefore, a negative sentinel node makes it highly unlikely that other nodes in the same lymphatic basin are affected. Although the long-term therapeutic benefit of the sentinel lymph node biopsy per se has not yet been ascertained, this procedure distinguishes patients without nodal metastases, who can avoid nodal basin dissection with its associated risk of lymphedema, from those with metastatic involvement, who may benefit from additional therapy. Sentinel lymph node biopsy would represent a significant advantage as a minimally invasive procedure, considering that an average of only 20% of melanoma patients with a Breslow thickness between 1.5 and 4 mm harbor metastasis in their sentinel node and are therefore candidates for elective lymph node dissection. Furthermore, histologic sampling errors (amounting to approximately 12% of lymph nodes in the conventional routine) can be reduced if one assesses a single (sentinel) node extensively rather than assessing the standard few histologic sections in a high number of lymph nodes per patient. The cells from which cutaneous melanomas originate are located between the dermis and the epidermis, a zone that drains to the inner lymphatic network in the reticular dermis and, in turn, to larger collecting lymphatics in the subcutis. Therefore, the optimal route for interstitial administration of radiocolloids for lymphoscintigraphy and subsequent radioguided sentinel lymph node biopsy is intradermal or subdermal injection. (99m)Tc-Labeled colloids in various size ranges are equally adequate for radioguided sentinel lymph node biopsy in patients with cutaneous melanoma, depending on local experience and availability. For melanomas along the midline of the head, neck, and trunk, particular consideration should be given to ambiguous lymphatic drainage, which frequently requires interstitial administration virtually all around the tumor or surgical scar from prior excision of the melanoma. Lymphoscintigraphy is an essential part of radioguided sentinel lymph node biopsy because images are used to direct the surgeon to the sites of the nodes. The sentinel lymph node should have a significantly higher count than that of the background (at least 10:1 intraoperatively). After removal of the sentinel node, the surgical bed must be reexamined to ensure that all radioactive sites are identified and removed for analysis. Virtually the entire sentinel lymph node should be processed for histopathology, including both conventional hematoxylin-eosin staining and immune staining with antibodies to the S-100 and HMB-45 antigens. The success rate of radioguidance in localizing the sentinel lymph node in melanoma patients is approximately 98% in institutions that perform a high number of procedures and approaches 99% when combined with the vital blue-dye technique. Growing evidence of the high correlation between a sentinel lymph node biopsy negative for cancer and a negative status for the lymphatic basin-evidence, therefore, of the high prognostic value of sentinel node biopsy-has led to the procedure's being included in the most recent version of the TNM staging system and starting to become the standard of care for patients with cutaneous melanoma.

Colloids↗
PubMed1981

Regression of area mortality rates on explanatory variables: what weighting is appropriate?

"One can often gain insight into the aetiology of a disease by relating mortality rates in different areas to explanatory variables. Multiple regression techniques are usually employed, but unweighted least squares may be inappropriate if the areas vary in population size. Also, a fully weighted regression, with weights inversely proportional to binomial sampling variances, is usually too extreme. This paper proposes an intermediate solution via maximum likelihood which takes account of three sources of variation in death rates: sampling error, explanatory variables and unexplained differences between areas. The method is also adapted for logit (death rates), standardized mortality ratios (SMRs) and log (SMRs). Two [United Kingdom] examples are presented."

Demography↗
PubMed1980

Intransitivity, the spatial interaction model, and U.S. migration streams.

"The flows predicted by a large class of spatial interaction models are transitive, yet US migration tables have been shown to contain large numbers of intransitivities. This paper investigates a number of possible conditions under which flows regulated by the spatial interaction model might be observed to be intransitive. A singly constrained gravity model is calibrated for a number of flow tables, and distorted by sampling error, by aggregation over strata, and by an independently distributed error term.... The results of the calibration of the spatial interaction using US interstate migration flows, 1935-1970, are given and compared with others previously published."

Americas↗