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Biomedical subjects

R Kay

Publications and source records attributed to R Kay.

At least 217 records · Page 12Linked to original sources
PubMed1984

Goodness of fit methods for the proportional hazards regression model: a review.

The proportional hazards regression model is now used extensively in survival time studies. Although the model (hazard function, lambda (t;x) = lambda 0 (t)e beta' x) can be considered to be partially distribution-free, the following assumptions regarding the distribution of survival time are made: 1. Hazard functions for any two individuals are proportional. Thus (Formula: see text) is independent of t. 2. Independent variables affect the log hazard in an additive way (Formula: see text) This paper reviews methods available for assessing these assumptions in particular cases.

Models, Theoretical↗
PubMed1983

Streptococcus suis meningitis. An important underdiagnosed disease in Hong Kong.

Streptococcus suis has been identified as the most common cause of meningitis in adults in Hong Kong. The disease is characterized by occupational exposure to pigs or pork. It occurs in summer, and is associated with early, severe, sensory deafness, arthritis, uveitis, and loss of balance. Examination of the cerebrospinal fluid may show an elevated white cell count with a predominance of either polymorphs or lymphocytes. Misinterpretation of the microbiological findings by inexperienced staff members may lead to a failure to correctly diagnose this disease. This is the first report of a series of cases of Strept. suis meningitis outside western Europe. Health authorities are urged to be aware of this disease in pork-consuming countries.

Adult↗
PubMed1983

99mTc-DMSA scanning to diagnose pyelonephritic scarring in children.

99mTechnetium-labeled dimercaptosuccinic acid (99mTc-DMSA) scanning provides superior quality images of renal parenchymal detail, which makes it highly sensitive for the diagnosis of pyelonephritic scarring. Unlike most other imaging techniques, radionuclide scanning is not affected by bowel gas or bony structures overlying the kidneys. This makes it particularly useful in children. Furthermore, renal scarring can be demonstrated by 99mTc-DMSA even before the classic gross anatomic and radiologic changes are present. The use of 99mTc-DMSA scanning in over 300 children has demonstrated its benefits and advantages over standard radiographic techniques.

Adolescent↗
PubMed1983

Adrenocortical carcinoma in children.

Adrenocortical carcinoma in childhood is a rare yet potentially fatal disease. We present 5 cases of adrenocortical carcinoma detected and managed in childhood. Of the 5 patients 4 presented with clinical signs of excess corticosteroid production and 1 presented suddenly with abdominal pain. All patients had palpable abdominal masses. All tumors were removed surgically and adjuvant therapy with mitotane was used in 4 children. Two patients are alive and 3 are dead. Our experience demonstrates that mitotane may be used safely in children, and that early diagnosis, aggressive surgical extirpation, and the use of mitotane and chemotherapy may lead to an increased survival of children with adrenocortical carcinoma.

Adolescent↗
PubMed1983

Haemolytic-uraemic syndrome: an analysis of prognostic features.

Seventy-two children with the haemolytic-uraemic syndrome were seen between 1969 and 1980 at The Hospital for Sick Children and Guy's Hospital, London. They probably constitute the majority of such cases in south-east England during that period. Boys and girls were affected equally, the mean age at presentation was 3.5 years, and a peak incidence of the disorder in summer months was observed. In 52 (72%) there was a history of diarrhoea at onset. Fifty-seven (78%) were managed by dialysis. Fifty (70%) of the 72 children had a favourable outcome with complete recovery, 3 (4%) died in the acute phase of the illness, 8 (11%) had residual hypertension or chronic renal failure, and 11 (16%) never recovered renal function. The probability of complete recovery of renal function was analysed by logistic regression which indicated that younger age, presentation in the summer months, diarrhoea at onset and, in those patients who were dialysed, a short prodromal illness were associated with a good outcome. Further analysis of the interaction among these variables in the patient group as a whole indicated that diarrhoea favoured a good outcome among boys but not girls.

Acute Kidney Injury↗
PubMed1983

Coronary thrombosis in the absence of angiographically-evident obstructive coronary disease.

A 31-year-old man with an acute myocardial infarction underwent intracoronary thrombolysis with streptokinase. Post-thrombolytic angiography revealed no underlying obstructive coronary disease. This particular syndrome of a documented thrombus in a normal vessel causing infarction has not previously been described. Such a sequence may explain the occurrence of myocardial infarction in some patients with normal coronary arteries. The mechanism by which thrombus occurs in an angiographically-normal coronary artery is at present undefined.

Adult↗
PubMed1982

Primary sick sinus syndrome as an indication for chronic pacemaker therapy in young adults: incidence, clinical features, and long-term evaluation.

Of 1484 pacemakers placed at our institution between 1970 and 1980, there were 18 patients between the ages 20 and 40 years who were not postoperative congenital heart disease cases. Twelve of these patients had primary sick sinus syndrome (SSS) as the indication for pacing. Eleven of 12 patients were markedly symptomatic with syncope, near syncope, or lightheadedness. Ambulatory monitoring revealed evidence of sinus node disease in all patients studied. Electrophysiologic studies were falsely negative in the five patients in whom they were performed. Patients tolerated pacemaker therapy well and became asymptomatic with pacing. We conclude that SSS in young adults is uncommon, but still represents the most common indication for permanent pacemaker therapy in this age group. The decision for pacemaker therapy should depend on symptoms and results of ambulatory monitoring. These patients can expect symptomatic improvement with pacing.

Adult↗
PubMed1982

On the use of hazard functions in breast cancer studies.

Hazard functions are nowadays used extensively by mathematicians as a tool in the analysis of survival data. They have been implicitly employed in medicine for many years to investigate 'curability'. The hazard function will be shown to be a natural concept which can help the clinician to express in a precise way his ideas concerning the disease process and the biology of treatment effect. The relationship between hazard and survivor function is discussed. Some historical comments about the interpretation of statistics in survival time studies are also made.

Breast Neoplasms↗
PubMed1981

Uroepithelial carcinoma in association with cyclophosphamide ingestion.

The association of daily oral cyclophosphamide with the development of transitional cell carcinoma or squamous cell carcinoma of the bladder had been documented. We report the first 2 cases of transitional cell carcinoma of the renal pelvis and an additional 4 cases of transitional cell carcinoma of the bladder following cyclophosphamide ingestion. Patients who have been taking daily oral cyclophosphamide for a prolonged period should have excretory urography, cystoscopy and bladder mucosal biopsies performed as part of a cancer surveillance protocol.

Aged↗
PubMed1981

Validity of routine clinical test weighing as a measure of the intake of breast-fed infants.

Routine clinical test weighing was carried out on 100 bottle-fed infants to assess the accuracy of the procedure; the feed intake was measured by weighing the feeding bottles before and after feeding. Test weight was found to be an unreliable indication of feed weight, underestimating the amount of feed actually taken at test weight values below 60 g, and overestimating the amount of feed taken at test weights over 60 g. The errors were largest in infants having test weights at the extremes of the range. Test weighing with clinical baby scales is an unreliable and inaccurate indication of feed intake in breast-fed infants.

Body Weight↗