Association between serum free thyroxine concentration and atrial fibrillation.

BACKGROUND: Previous studies have suggested that minor changes in thyroid function are associated with risk of atrial fibrillation (AF). Our objective was to determine the relationship between thyroid function and presence of atrial fibrillation (AF) in older subjects. METHODS: A population-based study of 5860 subjects 65 years and older, which excluded those being treated for thyroid dysfunction and those with previous hyperthyroidism. Main outcome measures included tests of thyroid function (serum free thyroxine [T(4)] and thyrotropin [TSH]) and the presence of AF on resting electrocardiogram. RESULTS: Fourteen subjects (0.2%) had previously undiagnosed overt hyperthyroidism and 126 (2.2%), subclinical hyperthyroidism; 5519 (94.4%) were euthyroid; and 167 (2.9%) had subclinical hypothyroidism and 23 (0.4%), overt hypothyroidism. The prevalence of AF in the whole cohort was 6.6% in men and 3.1% in women (odds ratio, 2.23; P<.001). After adjusting for sex, logistic regression showed a higher prevalence of AF in those with subclinical hyperthyroidism compared with euthyroid subjects (9.5% vs 4.7%; adjusted odds ratio, 2.27; P=.01). Median serum free T(4) concentration was higher in those with AF than in those without (1.14 ng/dL; interquartile range [IQR], 1.05-1.27 ng/dL [14.7 pmol/L; IQR, 13.5-16.4 pmol/L] vs 1.10 ng/dL; IQR, 1.00-1.22 ng/dL [14.2 pmol/L; IQR, 12.9-15.7 pmol/L]; P<.001), and higher in those with AF when analysis was limited to euthyroid subjects (1.13 ng/dL; IQR, 1.05-1.26 ng/dL [14.6 pmol/L; IQR, 13.5-16.2 pmol/L] vs 1.10 ng/dL; IQR, 1.01-1.21 ng/dL [14.2 pmol/L; IQR, 13.0-15.6 pmol/L]; P=.001). Logistic regression showed serum free T(4) concentration, increasing category of age, and male sex all to be independently associated with AF. Similar independent associations were observed when analysis was confined to euthyroid subjects with normal TSH values. CONCLUSIONS: The biochemical finding of subclinical hyperthyroidism is associated with AF on resting electrocardiogram. Even in euthyroid subjects with normal serum TSH levels, serum free T(4) concentration is independently associated with AF.

Prediction of all-cause and cardiovascular mortality in elderly people from one low serum thyrotropin result: a 10-year cohort study.

BACKGROUND: Low serum thyrotropin, in combination with normal concentrations of circulating thyroid hormones, is common, especially in elderly people and in individuals with a history of thyroid disease. We aimed to assess the long-term effects of subclinical hyperthyroidism on mortality. METHODS: We did a population-based study of mortality in a cohort of 1191 individuals not on thyroxine or antithyroid medication. All participants were aged 60 years or older. We measured concentration of thyrotropin in serum at baseline in 1988-89. We recorded vital status on June 1, 1999, and ascertained causes of death for those who had died. We compared data for causes of death with age-specific, sex-specific, and year-specific data for England and Wales. We also compared mortality within the cohort according to initial thyrotropin measurement. RESULTS: During 9733 person-years of follow-up, 509 of 1191 people died, the expected number of deaths being 496 (standardised mortality ratio [SMR] 1.0, 95% CI 0.9-1.1). Mortality from all causes was significantly increased at 2 (SMR 2.1), 3 (2.1), 4 (1.7), and 5 (1.8) years after first measurement in those with low serum thyrotropin (n471). These increases were largely accounted for by significant increases in mortality due to circulatory diseases (SMR 2.1, 2.2, 1.9, 2.0, at years 2, 3, 4, and 5 respectively). Increases in mortality from all causes in years 2-5 were higher in patients with low serum thyrotropin than in the rest of the cohort (hazard ratios for years 2, 3, 4, and 5 were 2.1, 2.2, 1.8, and 1.8, respectively). This result reflects an increase in mortality from circulatory diseases (hazard ratios at years 2, 3, 4, and 5 were 2.3, 2.6, 2.3, 2.3), and specifically from cardiovascular diseases (hazard ratios at years 2, 3, 4, and 5 were 3.3, 3.0, 2.3, 2.2). INTERPRETATION: A single measurement of low serum thyrotropin in individuals aged 60 years or older is associated with increased mortality from all causes, and in particular mortality due to circulatory and cardiovascular diseases.

Accuracy of routinely collected clinical data on acute medical admissions to one hospital.

Despite the rapid growth in routine computerized data collection within the National Health Service (NHS), and the increased use of such data for generating hospital statistics and doctor activity rates, few validation studies exist. During a study of 158 acute medical admissions, and examination of hospital data revealed numerous and systematic inaccuracies. If general practitioner (GP) performance statistics are to be reliably based on such sources, data validation, staff training, and protocols for data entry should form a routine part of NHS practice.

Acquisition of basic clinical skills in the general practice setting.

Undergraduate medical education in the UK is changing due to both education pressure (from the General Medical Council) and changes in the hospital service. As a result the role of general practice in providing core clinical experience is under debate. The purpose of this study was to determine the clinical contact available for junior clinical medical clerks (third year) attached to five general practices. We report here on the clinical experience recorded by students during 106 sessions (74% of possible sessions). One hundred and one patients were seen, 54% females; ages ranging from 14 to 92. Four hundred and twenty-six symptoms were recorded; the largest category (36%) was CVS/respiratory followed by neurological (20%). Shortness of breath was the commonest single symptom (46% in the CVS/respiratory category). Three hundred and seventy-one signs were recorded; 48% were in the CVS/respiratory category, 33% in the neurological category. Cardiac murmurs were the commonest single sign (34% of the CVS/respiratory category). Sixty-nine separate comments were made by students about the range of clinical experience available; all were favourable. Forty-eight per cent of comments highlighted the availability of patients with appropriate symptoms and signs. This study has demonstrated that general practices can provide appropriate clinical exposure which complements hospital teaching for junior students.

A qualitative investigation into why patients change their GPs.

BACKGROUND: In the past patients have rarely changed doctor. The UK Government has made such change easier and it appears to be becoming more common. Changing doctor without changing address may be indicative of dissatisfaction with the GP service. Previous research in this area has been largely quantitative. OBJECTIVE: To identify why patients change their GP although they have not moved house. METHOD: Qualitative investigation of patients' experiences. In depth interviews of 24 patients were conducted to determine why they had left their previous doctor. Letters describing the process of change were received from a further 17 patients. Analysis was performed using standard qualitative techniques. RESULTS: The decision to change was in most cases multi-factorial. Interviews yielded more detailed and richer accounts than letters. For interviewees, rudeness or the attitude of the doctor was the commonest reason. Overall, 19 different reasons, in four categories, were identified. The largest single category was accessibility, closely followed by attitudinal problems. Clinical issues and personal characteristics of the doctor were less common. The majority of those responding by letter gave only one reason, usually distance. CONCLUSION: Patients change doctor after careful consideration and commonly for interpersonal reasons. There is usually one critical factor in the decision to change. Factors may be modifiable or non-modifiable. Critical event audit may enable GPs to analyse the reasons why patients leave their lists.

Thyroxine prescription in the community: serum thyroid stimulating hormone level assays as an indicator of undertreatment or overtreatment.

Examination of thyroxine usage in a study in the United States of America revealed that many patients were prescribed thyroxine for non-thyroid indications, such as obesity and fatigue. Many of those receiving thyroxine had high or low serum thyroid stimulating hormone levels, indicating prescription of incorrect doses or lack of patient compliance with therapy. Long term thyroxine therapy may have effects upon the risk of osteoporosis. The aims of this study were to investigate indications for thyroxine prescription in the United Kingdom and to examine the frequency of abnormal serum thyroid stimulating hormone concentrations in those prescribed thyroxine for hypothyroidism. This was in order to determine the relevance of measurement of thyroid stimulating hormone level in monitoring thyroxine therapy. Subjects receiving thyroxine were identified from the computerized prescribing records of four general practices in the West Midlands. Of 18,944 patients registered, 146 (0.8%) were being prescribed thyroxine; 134 of these had primary hypothyroidism and the remainder had other thyroid or pituitary diseases prior to treatment. Of the 97 patients with primary hypothyroidism who agreed to have their thyroid stimulating hormone level measured, abnormal serum levels were found in 48%, high levels in 27% and low levels in 21%. There was a significant relationship between prescribed thyroxine dose and median serum thyroid stimulating hormone level: high hormone levels were found in 47% of those prescribed less than 100 micrograms thyroxine per day, while low levels were found in 24% of those prescribed 100 micrograms or more. Thus, thyroxine prescription was common in the four practices sampled, although indications for its use were appropriate.(ABSTRACT TRUNCATED AT 250 WORDS)

Circulating lipids and minor abnormalities of thyroid function.

OBJECTIVE: We determined the effect of subclinical hyperthyroidism (defined as low circulating TSH with normal serum free T4) and subclinical hypothyroidism (raised serum TSH with normal free T4) on fasting levels of blood lipids. DESIGN: Prospective study of lipid concentrations in patients identified as having abnormal TSH. PATIENTS: Patients were identified in a population screening study of those over 60 years, with persistently low TSH with normal free T4 (n = 27) or high TSH but normal free T4 (n = 57). Patients were matched to controls with normal serum TSH by age, sex and body mass index. MEASUREMENTS: Serum TSH, free T4, free T3, total cholesterol, low density lipoprotein (LDL) cholesterol and high density lipoprotein (HDL) cholesterol. RESULTS: Serum free T4 measurements were significantly higher in those with subclinical hyperthyroidism than in their controls (P < 0.001) and lower in those with subclinical hypothyroidism than in matched controls (P < 0.001). Measurement of fasting lipids in patients and controls revealed a marked (12.2%) reduction in serum total cholesterol in subclinical hyperthyroidism (P < 0.01); no significant difference in fasting lipids between patients with subclinical hypothyroidism and controls was observed. CONCLUSIONS: Differences in free T4 between those with low or high TSH and controls with normal TSH suggest that abnormalities of TSH directly reflect thyroid hormone excess and deficiency. A reduction in cholesterol in those with subclinical hyperthyroidism suggests a direct influence of thyroid hormone excess on lipid metabolism in these patients.

Long-term thyroxine treatment and bone mineral density.

Studies of the effect of thyroxine replacement therapy on bone mineral density have given conflicting results; the reductions in bone mass reported by some have prompted recommendations that prescribed doses of thyroxine should be reduced. We have examined the effect of long-term thyroxine treatment in a large homogeneous group of patients; all had undergone thyroidectomy for differentiated thyroid cancer but had no history of other thyroid disorders. The 49 patients were matched with controls for age, sex, menopausal status, body mass index, smoking history, and calcium intake score; in all subjects bone mineral density at several femoral and vertebral sites was measured by dual-energy X-ray absorptiometry. Despite long-term thyroxine therapy (mean duration 7.9 [range 1-19] years) at doses (mean 191 [SD 50] micrograms/day) that resulted in higher serum thyroxine and lower serum thyrotropin concentrations than in the controls, the patients showed no evidence of lower bone mineral density than the controls at any site. Nor was bone mineral density correlated with dose, duration of therapy, or cumulative intake, or with tests of thyroid function. There was a decrease in bone density with age in both groups. We suggest that thyroxine alone does not have a significant effect on bone mineral density and hence on risk of osteoporotic fractures.

Assessment of a screening process to detect patients aged 60 years and over at high risk of hypothyroidism.

General practitioners are increasingly expected to screen elderly patients for common disorders, such as hypothyroidism, and the identification of at-risk patients by simple means would reduce the financial and other costs of such screening. A general practice based study of 1193 patients aged 60 years and over has been carried out to investigate the usefulness of the following factors in identifying those in whom biochemical testing for hypothyroidism would be indicated: personal history or family history of thyroid disease, symptoms of thyroid disease and body mass index. Of the 190 patients with either a personal or family history of thyroid disease, 28 (14.7%) had an elevated concentration of thyroid-stimulating hormone. Thus, 66 of the 94 patients (70.2%) with elevated concentrations of thyroid-stimulating hormone had no such thyroid history. Similarly, only nine (4.7%) of the patients with a personal or family history of thyroid disease required thyroxine replacement therapy. Thus, 22 of the 31 patients (71.0%) requiring such treatment had no such history. Discriminant analysis of the responses of women patients to questions concerning personal or family history of thyroid disease, the presence of symptoms of hypothyroidism, their age and body mass index identified only 51.3% of those with an elevated thyroid-stimulating hormone concentration and 77.2% of those with normal thyroid-stimulating hormone. Analysis of the responses of the men patients was even less discriminating.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence and follow-up of abnormal thyrotrophin (TSH) concentrations in the elderly in the United Kingdom.

Increasing use of assays for TSH with improved sensitivity as a first-line test of thyroid function has raised questions regarding prevalence and clinical significance of abnormal results, especially values below normal. We have assessed the thyroid status of 1210 patients aged over 60 registered with a single general practice by measurement of serum TSH using a sensitive assay. High TSH values were more common in females (11.6%) than males (2.9%). TSH values below normal were present in 6.3% of females and 5.5% of males, with values below the limit of detection of the assay present in 1.5% of females and 1.4% of males. Anti-thyroid antibodies were found in 60% of those with high TSH but only 5.6% of those with subnormal TSH. Eighteen patients were hypothyroid (high TSH, low free thyroxine) and one thyrotoxic (low TSH, raised free thyroxine) at initial testing. Seventy-three patients with elevated TSH but normal free T4 were followed for 12 months; 13 (17.8%) developed low free T4 levels and commenced thyroxine, TSH returned to normal in four (5.5%) and 56 (76.7%) continued to have high TSH values. Sixty-six patients with TSH results below normal were followed. Of the 50 subjects with low but detectable TSH at initial testing, 38 (76%) returned to normal at 12 months; of those 16 with undetectable TSH followed, 14 (87.5%) remained low at 12 months. Only one subject (who had an undetectable TSH) developed thyrotoxicosis. In view of the marked prevalence of thyroid dysfunction in the elderly, we suggest that screening of all patients over 60 should be considered.(ABSTRACT TRUNCATED AT 250 WORDS)