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At least 73 records · Page 4Linked to original sources
PubMed1977

[The difficulty of choosing a good control group in a retrospective study (author's transl)].

The choice of either hospital or population controls in retrospective studies is guided by rules implying underlying hypotheses. In a study on aesophageal cancer in relation to alcohol and tobacco consumption, two such control groups were available and were compared. It was found that some of the currently accepted assumptions relating to representativeness of cases or controls were verified but many others were not, particularly in hospital controls. These were found to give less correct estimates of drinking and smoking habits than those obtained from population controls. The limitations in the use of either type of controls is discussed, in relation to the purpose of the study concerned.

Adult↗
PubMed1979

Synonymy of strains of Center for Disease Control group DF-1 with species of Capnocytophaga.

Of eight strains of Center for Disease Control group DF-1 examined, seven had 62 to 87% deoxyribonucleic acid homology with the neotype strain of Capnocytophaga ochracea and one had 72% deoxyribonucleic acid homology with the type strain of C. gingivalis. Deoxyribonucleic acid homology of four strains of Bacteroides ochraceus with the neotype strain of C. ochrecea was 76 to 86%.

Bacteroides↗
PubMed1987

[Childhood stress and neurosis--results of a control group study].

Biographical stress-risk was compared between a group of 68 neurotic-psychosomatic patients and a parallel control group matched in terms of age and sex. This risk rate was established using a so-called risk-index in which 8 known and variably weighted risk factors were taken into consideration. The following hypotheses were confirmed in the study: Neurotically ill persons show a higher stress-risk (risk-index) in their childhood and pre-adolescence than is found in healthy persons. A person's stress-index is related to the degree of neurosis (r = .42).

Adult↗
PubMed1989

Psychosocial factors, curative therapies, and behavioral outcomes. A comparison of testis cancer survivors and a control group of healthy men.

In a retrospective study of 223 testis cancer survivors and 120 controls matched sociodemographically, we examined the relative impact of sociodemographic and clinical factors on long-term outcomes in the areas of sexual function, relationships, employment, and mental outlook. For most of the survivors, testis cancer did not lead to unemployment (4.5%), divorce (6.8%), or disabling psychological problems. Multivariate analysis results confirm that cancer survivors report significantly more infertility and sexual performance distress, but not more desire distress, than the control group. Survivors' sexual impairment varied according to treatment received (and therefore histologic factors) and sociodemographic variables. Parental status (not having children) and education (college or less) independently predict infertility distress, whereas education and lower occupational level independently predicted sexual performance distress. Adjusting for socioeconomic status (SES), the men with advanced testis cancer who received chemotherapy and standard retroperitoneal lymph node dissection (RPLND) had significantly more infertility and performance distress than those men who received other treatments. Neither the treatment or SES variables predicted disrupted relationships or a deteriorated mental outlook. However, men with sexual impairment distress were more likely to report strained relationships and a pessimistic mental outlook. These findings have implications for treatment decisions and can be used to identify subgroups of survivors who could benefit from counseling and sexual rehabilitation services.

Adolescent↗
PubMed1987

Control groups for psychosocial intervention outcome studies.

In psychosocial outcome research, as contrasted to pharmacologic research, control groups receiving inert treatment, designed to raise expectations but otherwise provide no service, are almost never indicated; this is true because of methodologic as well as ethical reasons. Four types of comparisons suffice as alternatives: treatment versus no treatment, treatment versus minimal treatment, treatment A versus treatment B, and dismantling. When choices are made among these types of comparisons with power analysis and eight other factors taken into account, the questions of outcome research should be answerable with maximum economic efficiency, with maximum benefit to subjects, and without deception.

Costs and Cost Analysis↗
PubMed1990

[2 sample configuration frequency analysis: solitary and complementary discriminant types of treatment and control groups].

The paper entitled "Two-sample CFA: Solitary and complementary discriminant types of treatment- and control groups" suggests to modify 2-sample and c-sample CFA as follows: While singular patterns of attributes define solitary types, complementary pairs of patterns define complementary types which may be interpreted as poles of a type-defining factor in factor analysis. The new version of 2-sample CFA is illustrated in 2 examples from clinical psychology with patterns of scales and symptoms.

Depressive Disorder↗
PubMed1976

[Comparative studies on oral glucose tolerance and serum lipids under the influence of a new oral contraceptive (SH B 209 AB: 2 mg cyproterone acetate + 0.05 mg ethinyl estradiol), the combination D-norgestrel/ethinyl estradiol and in a control group (author's transl)].

24 healthy women given the combination of cyproterone acetate (2 mg) + ethynyl estradiol (0.05 mg) [SH B 209 AB] and D-norgestrel (0.25 mg) + ethinyl estradiol (0.05 mg) [Neogynon] were compared with a control group in oral glucose tolerance tests. The volunteers were divided into three groups. Two received alternately both preparations with each treatment cycle preceded by one cycle without medication. The third group served as an independent control. On the 25th day of each cycle blood was withdrawn before and 15, 30, 45, 60, 90 and 120 min after the carbohydrate load. Blood glucose and insulin and free fatty acids in serum were determined. Fasting values of triglycerides and cholesterol in serum were determined. The following results were obtained: 1. The mean fasting levels of blood glucose, serum insulin and free fatty acids were unchanged. 2. The total area under the blood glucose curve over the initial value was not altered 2 h after treatment with SH B 209 AB or Neogynon. The total area under the insulin and free fatty acids curves were also unchanged after the oral glucose load. 3. There was no change in serum cholesterol. 4. Serum triglycerides were significantly increased after SH B 209 AB. 5. The implications of the structural differences between both gestagens are discussed.

Blood Glucose↗
PubMed1987

Polychotomous logistic regression methods for matched case-control studies with multiple case or control groups.

Two statistical methods, a polychotomous and pairwise approach, are presented to derive estimates of the relative odds in a matched case-control design when multiple case or control groups are used. Test statistics are derived to determine if the relative odds between groups are different. The polychotomous method is limited to case-control sets, i.e., where data are available on all members of a matched set. In contrast, the pairwise method makes use of data from both complete and incomplete sets. Nonetheless, efficiency calculations show that the polychotomous logistic regression model is more efficient even when 40 per cent of the case-control sets are incomplete. An example using a single dichotomous variable is provided.

Adolescent↗
PubMed1992

[Lipid indicators of vascular risk. A cross-sectional study of a group of coronary patients, a group of subjects with normal coronary angiography and a control group].

During a transverse survey, 3 groups of men with the same weight and age were compared. Group I included 42 patients with coronary disease documented by coronarography, group 2 included 19 subjects with normal coronary angiograms, and group 3 included 27 healthy controls who had not undergone coronarography. Subjects presenting diabetes or any factor associated with secondary dyslipidemia or able to modify lipid levels were excluded from study. The following parameters were measured: total cholesterol (Chol), triglycerides (TG), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C), apoprotein A1 (apoA1), apoprotein B (apoB), lipoprotein (a) or Lp(a), fibrinogen, insulinemia and plasminogen activator inhibitor activity (PAI). The levels of chol, LDL-C and ApoB were the same in the 3 groups. The levels of TG, HDL-C, apoA1 and the ApoA-1/APoB ratio were significantly different between groups 1 and 2, on the one hand, and groups 1 and 3, on the other hand. The levels of Lp(a) and insulin were similar in the 3 groups. Fibrinogen levels were slightly higher in group 1 than in group 3. There was no significant difference between groups 1 and 2 with regard to any of the parameters. Subjects with angiographically normal coronary arteries and subjects with documented coronary disease exhibited similar lipid abnormalities. In this study, TG, HDL-chol, apoA1 and the apoB ratio were better predictors of cardiovascular risk than Chol, LDL-C or apoB.

Adult↗
PubMed1987

Confounding in epidemiologic studies: the adequacy of the control group as a measure of confounding.

A model for confounding in epidemiologic studies is developed based on the adequacy of the "control" group, instead of the widely used criterion of collapsibility, as a measure of confounding. It is shown that conditions for no confounding in both cohort and case-control studies derived under this model generally agree with the conditions for confounding derived inductively by Miettinen and Cook (1981, American Journal of Epidemiology 114, 593-603). The concept of confounding on which this model is based is compared with the collapsibility criterion in terms of its utility in the design and analysis of epidemiologic studies.

Biometry↗
PubMed1978

[Method of medical history taking and control group recruitment in oncoepidemiological studies].

Some methodical aspects of using the questionnaire as one of the basic tests, employed in oncoepidemiological investigations, are analysed. Under discussion is the potentialities and limits of the questionnairing method; the rules and ways of the optimum application of the given test to obtain the most comprehensive and objective enough information are reported. Also, the principles and criteria of selecting control groups in oncoepidemiological investigations are considered. The factors and conditions which may cause significant differences between the control and "test" groups irrespective of the genesis of the affection under study are discussed. An analysis is made of a number of typical methodical errors in oncoepidemiological investigations.

Clinical Trials as Topic↗
PubMed1979

[The hand in diabetes. Study of 97 diabetics compared to a control group].

To determine whether there is hand involvement specific to diabetes, 97 diabetics were compared with the same number of matched controls. Hands were examined with particular emphasis on skin, intrinsic muscles, articular mobility, sense of touch and vibration, digital systolic pressure, and radiological analysis of bones and joints. The most significant involvement, clearly present in 7 cases and less specifically in 12 other diabetics, included all of the following: atrophy and weakness of intrinsic muscles, painful interphalangeal rigidity limiting extension or flexion of the fingers, periarticular swelling of the phalanges, and trophic changes of the skin. Separately, these changes are not specific to diabetes: in the control group, although less frequent, they were found in patients aged 60 and over and are considered to be signs of senescence. Diabetes apparently accelerates the process of aging. Diabetic changes in the hand appear to be facilitated by neuropathy but not by arterial involvement. X-ray revealed a higher incidence of osteopenia and above all of vascular calcifications in the diabetic.

Adult↗
PubMed1975

Effect of rising intragastric pH induced by several antacids on serum gastrin concentrations in duodenal ulcer patients and in a control group.

The interrelationship of the effects of antacids and of rising intragastric pH on serum gastrin levels was examined by comparing the effect of three antacids (Mg(OH)2Al(OH)3, and CaCO3), and their nonbuffering chloride compounds (MgCl2, AlCl3, and CaCl2), on serum gastrin and intragastric pH in duodenal ulcer patients. In the case of calcium, the effect of CaCl2 with a pH of 10, and in another group, CaCl2 with a pH of 2, was studied. In the case of magnesium, a control group was also investigated. In another group, the effect of a nonionized suspension (BaSO4) was studied in order to assess the contribution of intragastric volume. Serum gastrin was determined radioimmunologically, and pH measurements were performed in vitro using a glass electrode. Serum gastrin concentrations rose significantly whenever intragastric pH was raised. Serum gastrin also rose after MgCl2, AlCl3, and CaCl2 with a pH of 2, when intragastric pH was not significantly altered. This rise, however, was significantly smaller than after administration of the antacids, except in the MgCl2-Mg(OH)2 and in the CaCl2 pH 10-CaCO3 groups. No significant rise of serum gastrin levels was observed after BaSO4. In nonulcer subjects, gastrin response was smaller than in the duodenal ulcer patients. The results suggest that administration of nonbuffering Mg-, Al-, and Ca-chlorides leads to elevated serum gastrin levels in duodenal ulcer patients; rising intragastric pH, however, exerts an additional serum gastrin response.

Adult↗
PubMed1989

Morphological changes of the ovarian surface epithelium in women with ovarian polycystic disease or endometrial carcinoma and a control group.

The ovarian surface epithelium and that of related inclusion cysts were studied in 50 women with ovarian polycystic disease and they were compared with our preceding observations performed on women with endometrial carcinoma (n = 50) and on women without any hyperplastic or neoplastic genital tract pathology (n = 50). In 16 women (32%) the ovarian epithelium with normal aspect was found on the surface of the ovary and in inclusion cysts. In the remaining 34 women (68%) surface papillomatosis, hyperplastic and metaplastic changes were present on the ovarian surface and/or in the inclusion cysts. These findings were similar to those observed in the group of women with endometrial adenocarcinoma, while the surface epithelium was often normal in the control group. Our observations confirm the hypothesis of a hormonal influence in the hyperplastic and metaplastic modifications of the ovarian epithelium and in the related common epithelial tumors of the ovary.

Adult↗
PubMed1991

[The effect of adhesive agents on the bonding strength of ceramic-composite. An in-vitro comparative study with 6 "porcelain primers" and a control group].

Orthodontic brackets were bonded to a total of 240 Biodent porcelain surfaces pretreated with a number of different porcelain primers. In a control group, 40 surfaces were pumiced, etched, rinsed and dried, and then bonded to similar brackets without the use of a primer. The test objects of group 1 (n = 140) and those of group 2 (n = 40) were tested for bond shearing strength in a material testing machine (Zwick 1441) after prior incubation in a corrosive fluid at a pH of 2.3 and a temperature of 37 degrees C for 24 hours and 21 days, respectively. The fracture sites were inspected and analysed. Incubation in corrosive fluid reduces the strength of the porcelain-composite bonding, the shearing strength and the number of fractures in the bonding decreasing. Damage to the porcelain was seen to occur after the use of Lee-Ortho-Prime and Bond-Por primers. All the primers tested can be used, although a bond shearing strength of less than 2 N/mm2 is at the lower limit of what can be accepted under the usual conditions of daily practice.

Ceramics↗
PubMed1992

A Piagetian framework as a basis for the assessment of cognitive organization in schizophrenia: a comparison of adolescent and adult patients to a normal control group.

Piaget's theoretical framework was utilized in this study to investigate the cognitive organization of schizophrenic patients. Data from a battery of eight Piagetian tasks of concrete and formal operations was collected for adolescent and adult-acute and chronic schizophrenic patients, and was compared to matched normal control groups. Findings show significant differences between patients and controls; among the patients' chronicity, age and hospitalization are contributing variables to lower cognitive performance. Concrete operational tasks in the physical and spatial domains are retained better than in the logico-mathematical domain, or formal operational tasks in all domains. Major problems appear in the ability to abstract general criteria and to mentally work with more than one dimension at a time. A logical approach to the solution of concrete problems and solving problems which seem to present a contradiction, or cause problems in the accommodation and integration of one's thinking. Further studies are needed in order to draw conclusions and to understand the implications for every day functioning, deficient in the schizophrenic patient.

Acute Disease↗