Clinical trials in chronic diseases.

In spite of rather negative publicity on the crossover/self-controlled design for clinical trials in the early 1980s, a fair number of these studies were published in that period. Using these studies as examples, we try to give an overview of major advantages and disadvantages of crossover and parallel group studies. Strengths of the crossover versus the parallel design include: (1) elimination of between-subject variability of symptoms; (2) no need for large samples; (3) fewer ethical problems; and (4) subjects are able to express their preference for one of the compounds being given.

Fundamental Issues of Choosing the Right Type of Trial.

BACKGROUND: Relevant advantages and disadvantages of crossover/self-controlled and parallel group studies are discussed. RESULTS: For ethicists crossovers are frequently less of a problem. Also, they may be less costly, and, in addition, statistically more powerful.

Changes in life-style in men under sixty years of age before and after acute myocardial infarction: a case-control study.

A case-control study was conducted to examine the presence of psychosocial factors before, during, and after acute myocardial infarction (AMI) in Dutch men under sixty years of age. The study included 42 AMI patients and 48 individuals in an age-adjusted sampled control group. The psychological factors included high level of psychological stress, of social isolation, type A1 and A2 behavior, and mental depression.

The risk of emergency intestinal bleeding among users of acenocoumarin: a population-based cohort study.

In spite of a 10-13 fold increased risk of bleeding, standard doses of coumarin with a target prothrombin time of 2.7-4.5 INR (International Normalized Ratio) are chronically used in the Netherlands by 4-5% of the adult population forty to eighty years old, mainly for the secondary prevention of myocardial infarction.

Selective determination of hydroxyproline in urine by high-performance liquid chromatography using precolumn derivatization.

A method to measure total hydroxyproline in human urine was developed. Primary amino acids were derivatized with ortho-phthaldialdehyde, followed by derivatization of imino acids with 9-fluorenylmethyl chloroformate. The fluorescent 9-fluorenylmethyl chloroformate derivatives were separated by reversed phase high-performance liquid chromatography.

Urinary excretion of six modified nucleosides by patients with breast carcinoma.

In this preliminary study we investigated the urinary excretion of pseudo-uridine, 1-methyl-adenosine, 1-methyl-inosine, 1-methyl-guanosine, 2-methyl-guanosine and N2,N2-dimethyl-guanosine in 22 patients with breast carcinoma, 16 with metastases. In 88% of the patients with metastatic breast carcinoma, at least one nucleoside level was elevated above the reference range; in 69% of cases at least two nucleoside levels were elevated; whereas three patients had all the six modified nucleosides elevated. Of the six patients without metastases, only one had one modified nucleoside level that was elevated.

Immunological indices in the cerebrospinal fluid of patients with presenile dementia of the Alzheimer type.

In ten patients with presenile dementia of the Alzheimer type and in a control group the levels of the different immunoglobulins were determined in both serum and cerebrospinal fluid (CSF), and gel electrophoretic techniques used to determine possible oligoclonal bands in the gamma-globulin region. There is no indication that patients with Alzheimer disease produce immunoglobulins within the central nervous system.