Modeling the diagnosis of stroke at two hospitals.

A comparison of five major categories of stroke in 651 patients revealed significant differences in the frequencies of diagnoses at the Beth Israel and Massachusetts General hospitals in Boston, Mass. (P less than 0.001 by chi-square test). To analyze these differences, we modeled the diagnostic process at each hospital with a Bayesian procedure and performed a crossover study in which each patient was rediagnosed by the model from the opposite hospital. The results indicate that the differences in the frequency of lacune and subarachnoid hemorrhage were associated with the patient population, whereas the differences in the frequency of embolism and atherothrombosis were associated with the diagnostic process. There was a marked difference in the use of arteriograms on the two stroke services, but no difference in morbidity or mortality. The modeling procedure described can be used to compare clinical processes when the allocation of patients is thought to be biased.

Variation in antenatal testing over time and between clinic settings.

Variation in the use of diagnostic procedures may be due to characteristics of patients, physicians, or their environment. Testing rates for 24-hour urinary estriol levels (EST), diagnostic ultrasound, and antepartum fetal heart rate testing (AFHRT) were examined in 8,527 deliveries from 1975 through 1978. Over the period, utilization of EST remained constant at about 7% of deliveries, while ultrasound increased from 20% to 35% and AFHRT, from 7% to 12%. This increase persisted after stratifying patients on a multivariate confounder score using 45 items of clinical information. Those receiving antenatal care in a hospital-based group practice or a resident-staffed community clinic were more likely to be tested than patients seen in private offices or a prepaid group practice.

Healing of port-wine stains after argon laser therapy.

Studies have shown port-wine stains (PWSs) probably represent an aneurysmal dilation and ectasia of the cutaneous vascular plexus. The abnormal vessels are largely included within a 0.6-mm subepidermal zone, which is within the argon laser destruction range. Twenty-eight patients with PWSs underwent biopsies prior to argon laser treatment and repeated biopsies 4 1/2 months later. Those lesions (23) that contained large ectatic blood-filled vessels responded well to argon laser therapy in contrast to those (five) in which the vessels were relatively small and erythrocyte free. A similar histologic pattern was seen in the repeated biopsy specimens of both groups: the mean vessel area, the fraction of dermis occupied by vessels, vascular erythrocyte content, and vessel wall thickness sharply decreased, while the number of vessels tripled. Since lesion color strongly correlates with and probably is largely determined by erythrocyte content, the reason for the PWS lightening, despite increased vessel number, is the relative lack of erythrocytes in the newly formed vessels.

The nature and evolution of port wine stains: a computer-assisted study.

In an attempt to understand the histogenesis and evolution of port wine stains (PWS), 100 patients with PWS were biopsied; the gross features of each lesion and the patient's associated clinical characteristics were recorded. A detailed analysis of each biopsy including both vessel and nonvessel parameters was made with the assistance of a computer. The central abnormalities characterizing port wine stains are an increase in vessel number (vascular profiles) and ectasia. Vessel number is highest in the immediate subepidermal area and then rapidly diminishes; mean vessel depth is .46 +/- .17 mm. In contrast mean vessel area shows less variation throughout the dermis, ectatic vessels being present when vessel number is very low. The product of both factors determines the percent of dermis occupied by vessels, but the mean vessel area is the major determinant. While age correlates poorly with vessel number, it correlates well with both progressive vessel ectasia and color shifts (pink to purple). Each of multiple vessel parameters analyzed (vessel number, mean vessel area, wall thickness, angulation, and luminal erythrocyte content) exhibited strong layer to layer correlation within the first .8 mm of tissue beneath the epidermis, indicating homogeneity of vessel characteristics within the lesion. The size of the lesion and facial quadrant distribution do not change with age nor are they related to any histological parameters. However the PWS lesion is found most often on the right side and lower quadrants, with a distinctive pattern being present in patients with glaucoma and mental retardation.

Port wine stains and the response to argon laser therapy: successful treatment and the predictive role of color, age, and biopsy.

To date, no criteria exist for anticipating the response of a port wine stain to argon laser therapy. In an effort to determine such predictive factors, the preceding study was undertaken. Sixty-two patients, ages 7 to 66 years, with port wine stains were biopsied, had a small test area treated, and were evaluated after 4 months. A desirable result, defined by marked lightening of the lesion without scarring, occurred in 73 percent of the patients. Factors favoring a desirable result included age greater than 37 years, purple color, fraction of dermis occupied by vessels greater than 5 percent, mean vessel area greater than 2500 micrometers2, and percent of vessels containing erythrocytes greater than 15 percent. Furthermore, the degree of color change strongly correlated with these indices. Factors indicating an undesirable result included age less than 17 years, pink color, vascular area less than 2 percent, mean vessel area less than 1500 micrometers2, and percent of vessels containing erythrocytes less than 3 percent, Thus, if appropriate clinical and histological criteria are met port wine stains can successfully treated with argon laser therapy.

Antinuclear antibodies and oral methoxsalen photochemotherapy (PUVA) for psoriasis.

In view of theoretical concern that psoralen ultraviolet A radiation (PUVA) therapy might induce a systemic lupus erythematosus-like syndrome, we studied serum antinuclear antibodies (ANAs) in patients with psoriasis who received PUVA and are participating in a five-year prospective study. At 14 centers, 1,023 patients had two or more ANA determinations. When first and last tests were compared, the incidence of positive tests for ANAs was not significantly different (P greater than .2). In addition, there was no apparent relationship between the frequency of PUVA treatments and the probability of a positive test. Over a two-year period, there is no evidence to indicate that PUVA therapy for psoriasis has resulted in a significantly higher number of positive tests for ANAs within our population.