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  • 1
    Electronic Resource
    Electronic Resource
    Allgemeine Anforderungen an Studiendesigns (1994)
    Springer
    Der Anaesthesist 43 (1994), S. 1-8 
    Details
    ISSN: 1432-055X
    Keywords: Schlüsselwörter: Studiendesign – Biometrische Prinzipien – Kohortenstudie – Fall-Kontroll-Studie – Randomisierte klinische Studie – Intention-to-treat-Prinzip ; Key words: Study design – Biometric principles – Cohort study – Case-control study – Randomized clinical trial – Intention-to-treat principle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract. It is the purpose of this review to outline the principles of biometric methods in clinical research. Several study designs such as cohort studies, case-control studies or randomized controlled trials are explained in detail, and their problems and their interpretation are discussed. It is demonstrated that observational studies may yield valuable information about associations between exposure and outcome variables but that only properly designed randomized clinical trials of adequate sample size make it possible to answer research questions about causal relationships. It is emphasized that good clinical research depends on properly designed studies more than on complicated statistical procedures.
    Notes: Zusammenfassung. Es wird ein Überblick über die Struktur medizinisch-empirischer Forschungsmethodik gegeben. Verschiedene Versuchsdesigns wie Kohortenstudie, Fall-Kontroll-Studie und randomisierte klinische Studie werden dargestellt, erläutert, und es wird auf Probleme hingewiesen. Auf wichtige Aspekte randomisierter Studien wird im Detail eingegangen und dargestellt, daß sie die einzige Möglichkeit sind, in einer empirischen Wissenschaft wie der Medizin zu Aussagen über kausale Zusammenhänge zu gelangen. Es wird argumentiert, daß sich die biometrischen Anforderungen an klinische Forschung nicht durch die Anwendung komplexer statistischer Verfahren erfüllen lassen, sondern daß in diesem Sinne gute klinische Forschung ganz vorrangig von einer sorgfältigen Studienplanung abhängt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00013234
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  • 2
    Electronic Resource
    Electronic Resource
    Empirische Untersuchung zur Einschätzung diagnostischer Verfahren am Beispiel des Haemoccult-Tests (1986)
    Springer
    Journal of molecular medicine 64 (1986), S. 1106-1112 
    Details
    ISSN: 1432-1440
    Keywords: Diagnostic test ; Mass screening ; Occult blood ; Colonic neoplasms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We offered a questionnaire to 52 physicians in order to study the appreciation of the fecal occult blood test as an example of a diagnostic procedure. We asked for an indication of the over-all appreciation of the test, and for an estimation of the probabilities of colorectal cancer before the test and with a positive or a negative test result — each of them for three situations with different a priori probabilities. The answers demonstrated that the estimated value of the test, representing the personal experience of the physicians is very low (predictive factor between 0.61 and 0.78). About half of the physicians' estimations showed no improvement of probability by using Haemoccult. This contrasts with the expressed very positive general opinion about Haemoccult testing, including its use in symptomatic patients. This result underlines the necessity of careful evaluation of diagnostic tests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01726870
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  • 3
    Electronic Resource
    Electronic Resource
    Die Grundlagen der Validierung einfacher, diagnostischer Tests (1988)
    Springer
    Journal of molecular medicine 66 (1988), S. 655-661 
    Details
    ISSN: 1432-1440
    Keywords: Diagnostic tests ; Sensitivity ; Specificity ; Predictive value
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The fundamental terms in the evaluation of diagnostic tests are described and the differences to corresponding test parameters in clinical chemistry are emphasized. The derivation of a two-by two contingency table is explained in detail and basic characteristics of diagnostic tests, i.e. sensitivity and specificity as well as their independence of the prevalence (in the sense of a-priori-probability) is pointed out. The importance of the so-called predictive values is shown graphically, also the problem of selecting a cut-off-level (discrimination value) for the evaluatation of quantitative data. The various attempts to find a single value for the description of a diagnostic test are discussed and it is stressed that there is no principal necessity to use other terms than those mentioned above. Nevertheless it is possible to give a prevalence-independent measure which has some additional advantages in rating and comparing simple diagnostic tests.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01726922
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  • 4
    Electronic Resource
    Electronic Resource
    Kritische Evaluation von Fructosamin als Kontrollparameter in der Beurteilung der diabetischen Stoffwechseleinstellung (1989)
    Springer
    Journal of molecular medicine 67 (1989), S. 1066-1067 
    Details
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01727010
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  • 5
    Electronic Resource
    Electronic Resource
    Neurologische Skalen als Endpunkte in Schlaganfallstudien Aspekte der statistischen Auswertung (2000)
    Springer
    Der Nervenarzt 71 (2000), S. 797-801 
    Details
    ISSN: 1433-0407
    Keywords: Schlüsselwörter Ischämischer Schlaganfall ; Thrombolyse ; National Institute of Health Scale ; Modified Rankin Scale ; Barthel-Index ; Keywords Ischaemic stroke ; Thrombolysis ; National Institute of Health Scale ; Modified Rankin Scale ; Barthel Index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract Even after publication of ECASS II, the latest paper in a series of large, placebo-controlled studies on thrombolysis in acute ischaemic stroke, there is still uncertainty as to what the best clinical endpoint(s) is (are) in trial design for reliably identifying significant differences between treatment groups. If the expected treatment difference as measured by a neurological outcome scale like the Modified Rankin Scale corresponds more to a shift in dispersion (on average a majority of patients profits greatly) rather than to a shift in location (on average each patient profits much), then the power of the odds ratio test is much higher than that of the Wilcoxon test and therefore the clinical outcome parameters should be dichotomised. With respect to the time window of 0–6 hrs from symptom onset of an acute ischaemic stroke, for example, a dichotomisation of 0–2 vs. 3–6 for the Modified Rankin Scale is reasonable. In the case of multiple endpoints, a global (multivariate) test should be used, but the correlation between these endpoints must not be too high, which means that the various manifestations of the complex stroke disease should be considered.
    Notes: Zusammenfassung Auch nach dem Erscheinen der ECASS-II-Studie als bisher letzte Veröffentlichung einer Serie von großen, plazebokontrollierten Studien zur systemischen Thrombolyse beim akuten ischämischen Schlaganfall stellt sich hinsichtlich des Studiendesigns weiterhin die Kardinalfrage, welche(r) Endpunkt(e) am geeignetsten ist (sind), um Unterschiede zwischen den Behandlungsgruppen zuverlässig herausarbeiten zu können. Falls der Therapieeffekt, gemessen anhand neurologischer Endpunkte wie z. B. der Modified Rankin Scale, mehr einem Dispersionsunterschied (d. h. im Mittel profitiert eine Mehrzahl von Patienten viel) als einem Lokationsunterschied (d. h. im Mittel profitiert jeder Patient ein wenig) entspricht, bei welchem der Odds-Ratio-Test eine deutlich höhere Power aufweist als der Wilcoxon-Test, so sollten die Endpunkte dichotomisiert ausgewertet werden. Für das Zeitfenster von 0–6 h seit Beginn der Symptomatik des ischämischen Schlaganfalls ist beispielsweise für die Modified Rankin Scale die Dichotomisierung 0–2 vs. 3–6 sinnvoll. Werden multiple Endpunkte erhoben und ein globaler Test verwendet, so sollte sicher gestellt sein, dass diese nicht zu hoch korrelieren, d. h. verschiedene Dimensionen des komplexen Erkrankungsbildes Schlaganfall erfasst werden.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001150050666
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  • 6
    Electronic Resource
    Electronic Resource
    Colorectal carcinoma and Haemoccult (1987)
    Springer
    International journal of colorectal disease 2 (1987), S. 223-228 
    Details
    ISSN: 1432-1262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Meta-analysis has been performed on the world literature relating to Haemoccult screening for colorectal cancer. The analysis indicated a sensitivity of about 50%, specificity of about 97%, positive predictive value of 4.3% and negative predictive value of 99.85%. These figures assume a prevalence of colorectal cancer in the population of 0.3%. A model calculation using these figures together with some additional realistic assumptions suggests no reduction in mortality compared to an unscreened population. It is concluded that many questions about faecal occult blood screening remain and that uncontrolled mass population screening is not justified at this stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01649510
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  • 7
    Electronic Resource
    Electronic Resource
    Beurteilung klinischer Studien Hinweise zum kritischen Literaturstudium (1997)
    Springer
    Der Internist 38 (1997), S. 337-343 
    Details
    ISSN: 1432-1289
    Keywords: Schlüsselwörter Klinische Studien ; Auswertung ; Klinische Studien ; Planung ; Studiendesign
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zum Thema Es gibt eine Reihe methodischer Kriterien, nach denen wissenschaftliche Studien in Hinblick auf ihre Qualität und Aussagefähigkeit bewertet werden können. Aber auch diejenigen, die keine Spezialisten für Studiendesign sind und ”nur” die Studienergebnisse zur Kenntnis nehmen und diese für mehr oder weniger glaubwürdig halten, kurzum: die weitaus überwiegende Zahl unserer Leser, sollte über Basiskenntnisse auf dem Gebiet der Validierung wissenschaftlicher Resultate verfügen. Für sie ist diese Übersichtsarbeit geschrieben, damit sie imstande sind, sich ein besseres Urteil zu bilden, und nicht nur nach vagen Gesichtspunkten subjektive Urteile fällen. So können, wie hier erläutert, an jede Studie auch von Nichtspezialisten gezielt Fragen gestellt werden. Gerade in einer Zeit (und leider auch in einem Land!), in der paramedizinische und sogenannte alternative medizinische, nicht wissenschaftlich validierte Lehren unverhältnismäßig ernstgenommen werden, erscheint es notwendig, den kritischen Lesern auch die Bewertungskriterien darzustellen, mit deren Hilfe sie selbst zu begründeten Urteilen kommen können.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001080050045
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  • 8
    Electronic Resource
    Electronic Resource
    Effect of pressure and gas type on intraabdominal, subcutaneous, and blood pH in laparoscopy (2000)
    Springer
    Surgical endoscopy and other interventional techniques 14 (2000), S. 367-371 
    Details
    ISSN: 1432-2218
    Keywords: Key words: Pneumoperitoneum — CO2— Helium — Blood pH — Intra-abdominal pH — Subcutaneous pH — Laparoscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: According to the literature, the number of port-site metastases in laparoscopic surgery varies considerably depending on the type of gas used for the pneumoperitoneum. In order to investigate this observation we studied the changes in blood, subcutaneous, and intra-abdominal pH during laparoscopy with helium, CO2 and room air in a rat model. In addition, we looked at the influence of intra-abdominal pressure and duration of pneumoperitoneum on the pH during the laparoscopy. Methods: pH was measured by tonometry, intra-abdominally and subcutaneously. A pH electrode was additionally placed into the subcutaneous tissue and the results compared to those measured by tonometry. Blood samples were taken from a catheter in the carotid artery. The intra-abdominal pressure was 0, 3, 6, 9 mmHg for 30 min in each case. We investigated the effect of pneumoperitoneum with CO2, helium and air in randomized groups of 5 rats. In an additional series the pressure was held constant at 3 mmHg and the pH was measured every 30 min. Results: Due to the different absorption capacity of the peritoneum, laparoscopy with CO2 decreases the subcutaneous pH from 7.35 to 6.81. Blood pH is reduced from 7.37 to 7.17 and the intra-abdominal pH from 7.35 to 6.24. Other, less absorbable gases induce smaller changes of blood and subcutaneous pH (only 10% of CO2). In a variance analysis the p value is less than 0.001. The influence of duration of laparoscopy (30 min vs 90 min) on the subcutaneous pH is less compared to the influence of intra-abdominal pressure (0, 3, 6, 9 mmHg). Conclusions: Depending on the type of gas (CO2, air, helium) used for laparoscopy blood, subcutaneous and intra-abdominal pH are influenced differently. Because lower pH is known to impair local defense mechanisms, these results may be one explanation for the higher incidence of port-site metastasis in laparoscopy with CO2 than with other gases, as reported in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004640000156
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  • 9
    Electronic Resource
    Electronic Resource
    Short- and long-term results after laparoscopic vs conventional colon resection in a tumor-bearing small animal model (2000)
    Springer
    Surgical endoscopy and other interventional techniques 14 (2000), S. 561 -567 
    Details
    ISSN: 1432-2218
    Keywords: Key words: Colon resection — Immune response — Laparoscopy — Long-term results — Postoperative recovery — Stress parameter — Tumor-bearing small animal model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: We designed a study to evaluate the short- and long-term outcome of laparoscopic vs conventional colonic resection in a tumor-bearing small animal model. Methods: We operated on male BD X rats (260–300 g), performing either laparoscopic (n= 9) or open colon resection (n= 9) in order to evaluate stress and immunological response to laparoscopic vs conventional colon resection. A third group (n= 9) underwent anesthesia only. Immediately before and after surgery, as well as at 1, 7, and 21 days postoperatively, a sample of 1 ml blood was taken from the retrobulbar venous plexus. Stress (corticosterone) and immune parameters (neopterine and IL-1β, IL-6) and body weight as a parameter of postoperative recovery were measured to identify short-term alterations. Long-term changes were evaluated in terms of survival time and at autopsy by measuring the tumor weight and the number of tumor infiltrated nodules (histology). Results: The analysis of variance (ANOVA) showed significant differences between the three groups over a period of 1 week (p 〈 0.001 for corticosterone, p= 0.009 for neopterine, p= 0.04 for IL-1β, p= 0.024 for IL-6). Additionally, significant differences by t-test were found between the laparoscopic (minor alteration) and conventional (major alteration) group regarding corticosterone (p= 0.0015), neopterine (p= 0.0024), IL 1-β (p= 0.033), and IL-6 (p= 0.015) at the end of the operation. One week after the operation, the body weight was different depending on the type of operative procedure: 7 days postoperatively the rats lost 8% of their body weight after open surgery but only 4.3% after laparoscopic surgery. After anesthesia only, body weight increased by ∼4.8%. The medium survival time for the lap group was 44 days, whereas it was 44.1 days for the conventional group and 46 days for the anesthesia group (ANOVA p= 0.625). The number of nodules was 13.5 in the laparoscopic group 10.5 in the open group, and 7.4 in the anesthesia group, (ANOVA p= 0.119). The tumor weight was 6.8 g in the laparoscopic group, 6.4 g in the open group, and 5.04 g in the anesthesia group (ANOVA p= 0.874). Conclusion: In a tumor-bearing small animal model, laparoscopic colon resection alters the stress and immune system less than open colon resection. This observation has no implications for the long-term results as measured by survival time and at autopsy. Therefore, laparoscopic colon resection has a short-term benefit and has no negative effect on long-term results compared to conventional operative procedures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004640000130
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  • 10
    Electronic Resource
    Electronic Resource
    Prospective randomized study of stress and immune response after laparoscopic vs conventional colonic resection (1998)
    Springer
    Surgical endoscopy and other interventional techniques 12 (1998), S. 963-967 
    Details
    ISSN: 1432-2218
    Keywords: Key words: Laparoscopic colon resection — Stress parameter — Immune response — Postoperative recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Methods: In order to evaluate the stress and immunological response to laparoscopic and conventional colon resection we operated on male Wistar rats (350–380 g), performing either laparoscopic (n= 15) or open colon resection (n= 15). A third group (n= 10) underwent anesthesia only. Immediately before and after surgery as well as 1 and 7 days postoperatively a 1 ml sample of blood was taken from the retrobulbar veinous plexus. Stress (corticosterone) and immune parameters (neopterin and interleukin [IL] 1-β) were measured. Furthermore, the body weight as a parameter of postoperative recovery was monitored. Results: The analysis of variance showed significant differences between the three groups over a period of 1 week (p 〈 0.0001 for corticosterone, p= 0.0854 for IL 1-β, p= 0.0045 for neopterin). Additionally in a t-test significant differences were found between the laparoscopic and conventional group with regard to corticosterone (p= 0.08), to neopterin (p= 0.045), and to IL 1-β (p= 0.0043) at the end of the operation. One week after the operation the stress and immune parameters were back to normal levels in each group except IL 1-β, but the recovery indicated by body weight was different according to the kind of the applied operative procedure: 7 days postoperatively the rats lost 5.99% of their body weight after open surgery and only 2.4% after laparoscopic surgery. After anesthesia only the body weight increased by about 4.8%. Conclusion: Laparoscopic colon resection alters the stress and immune system of healthy rats less than open colon resection. This observation is confirmed by the quicker recovery in laparoscopically operated rats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004649900757
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