Psychologically mediated effects of diagnostic tests.

Laboratory tests are purported to affect patients even if they have no diagnostic values. We tested this hypothesis by measuring clinical outcomes of 176 patients thought clinically to have nonspecific chest pain. They were randomly allocated either to have a routine electrocardiogram and serum creatine phosphokinase tests (test group) or to have all diagnostic tests withheld (no-test group).

Involuntary weight loss: diagnostic and prognostic significance.

We prospectively evaluated 91 patients with involuntary weight loss. Thirty-two (35%) had no identifiable physical cause of weight loss, whereas the remainder had various physical illnesses. During the year after the index visit, 23 (25%) of the patients died and another 14 (15%) deteriorated clinically.

The diagnosis of abdominal pain in ambulatory male patients.

The purpose of this study was to identify clinical characteristics that could predict the diagnosis in ambulatory patients with abdominal pain. We studied 552 unselected ambulatory male patients whose average age was 47 years and whose median duration of pain was 3 weeks. Potentially serious disease occurred in 21% of the patients.

Assessment of patients' preferences for therapeutic outcomes.

We sought to characterize patients' preferences in drug therapy decisions with uncertain outcomes by analyzing their responses to hypothetical therapeutic scenarios. In each scenario, the patient chose between two drugs with equivalent effects, one having two possible outcomes occurring by chance (uncertain outcome) and the other having a single outcome (certain outcome). Most patients chose a certain and intermediate therapeutic effect rather than taking a chance between no effect and a very large favorable effect.

Diagnosing pancreatic cancer--an analysis of several strategies.

The usefulness of a clinical examination was compared with several other procedures (ultrasonography, pancreatic function tests, endoscopic retrograde cholangiopancreatography and angiography) for diagnosing pancreatic cancer. We used a simplified form of decision analysis to show the effects of different strategies on direct diagnostic costs, missed diagnoses and false-positive diagnoses. Our analysis indicates that existing laboratory tests are either too non-specific or too invasive to be used successfully as screening tests for pancreatic cancer.

The clinical value of the upper gastrointestinal tract roentgenogram series.

We studied the role of the upper gastrointestinal tract roentgenogram series (UGI) in the care of 483 ambulatory patients with varied abdominal complaints. The test was significantly abnormal about 20% of the time, rarely led to changes in therapy, and was ordered inappropriately 30% of the time (according to criteria devised by experts). Regardless of their test results, most patients' symptoms improved in the several months after the test.

Quality of patient care by nurse practitioners and physician's assistants: a ten-year perspective.

A remarkable development in primary care is the recent emergence of a new class of health professional: nurse practitioners and physician's assistants. These practitioners diagnose and treat a wide variety of medical problems, usually with supervision by physicians. Their clinical competence has been evaluated in over 40 studies.

Attachment of carbohydrate to the variable region of myeloma immunoglobulin light chains.

Approximately 15 per cent of the light chains from homogeneous immunoglobulins in patients with multiple myeloma contain an oligosaccharide group. Five human myeloma light chains that contained carbohydrate were studied. The sequence Asn-[unk]-Ser/Thr was at the site of carbohydrate attachment in all light chains.

Solid-pse radioimmunoassay of protein biosynthesis.

Solid-phase radioimmunoassay was used for measuring the rate of radioisotope incorporation into a single protein species. Radioactive antigen was measured by its binding to specific antiserum covalently linked to insoluble bromoacetylcellulose. The insoluble antigen-antibody complex was collected on filters for counting.