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Biomedical subjects

D W Clark

Publications and source records attributed to D W Clark.

At least 19 recordsLinked to original sources
PubMed2001

Is there an association between selective serotonin reuptake inhibitors and risk of abnormal bleeding? Results from a cohort study based on prescription event monitoring in England.

OBJECTIVE: To investigate whether an association between the use of selective serotonin reuptake inhibitor (SSRI) antidepressants and abnormal bleeding is demonstrated in a large population study. METHODS: An observational cohort study using cohorts from the Drug Safety Research Unit's prescription event monitoring database was performed. RESULTS: Analysis of combined haemorrhagic event rates calculated for the first 6 months of treatment for four SSRIs showed no significant difference between the rate for abnormal bleeding in the first month after starting treatment compared with months 2-6 [difference in rates 0.63 per 1000 patient months of treatment, 99% confidence interval (CI) -0.4, 1.67]. Comparison of the rates for the exposed combined SSRI cohort with the unexposed non-psychiatric drug cohort for the first month [relative risk (RR) 1.38, 95% CI 0.82, 2.34] and months 2-6 (RR 1.17, 95% CI 0.81, 1.68) showed no significant differences after adjustment for age and gender. However, there was a tendency towards highest risk with the combined SSRI cohort and lowest with the baseline cohort. CONCLUSION: This study provides weak evidence to support the hypothesis of a link between SSRIs and precipitation of bleeding events at a population level. The 95% CI is consistent with a possible risk of bleeding associated with SSRI users versus non-psychiatric drug users in the first month. Fuller consideration of confounding would be possible using follow-up of identified cases in a nested case-control study.

Age Distribution↗
PubMed2001

Profiles of hepatic and dysrhythmic cardiovascular events following use of fluoroquinolone antibacterials: experience from large cohorts from the Drug Safety Research Unit Prescription-Event Monitoring database.

OBJECTIVE: To investigate how frequently serious dysrhythmic cardiovascular, and hepatotoxic events are reported during routine clinical use of fluoroquinolones (quinolones) in general practice. DESIGN: Cohorts prescribed quinolones (cohort sizes: ciprofloxacin 11 477; enoxacin 2790; ofloxacin 11 033 and norfloxacin 11 110; mean age in each cohort of 48.6 to 57.0 years) were selected from the Drug Safety Research Unit's Prescription-Event Monitoring (PEM) database. The monitoring periods were November 1988 to January 1989 for ciprofloxacin; April 1989 to January 1991 for enoxacin; May 1991 to December 1991 for ofloxacin and October 1990 to October 1991 for norfloxacin. Data collected over the total PEM surveillance period on selected gastrointestinal events were extracted and reviewed to identify possible hepatic events, together with selected cardiovascular events associated with dysrhythmias. For each quinolone, times to onset of the event and patient-months of observation (denominator values) were calculated. The analysis was based on two observation periods: rate of event during the first 7 days following dispensing of a prescription for each drug (W(1)), and rate of event during the second to sixth week inclusive (W(2)). RESULTS: Scrutiny of original green forms revealed no evidence of drug-induced hepatic dysfunction within 42 days of drug administration for any of the quinolones monitored. No evidence was found of drug-induced dysrhythmic events associated with enoxacin within 42 days of drug administration. Of the other quinolones, 'atrial fibrillation' was reported most often within 42 days following ciprofloxacin administration, with no change in event rate over that time, crude relative risk (CRR)[W(1)/W(2)] 1.0 [95% confidence interval (CI) 0.02 to 8.92]. Other less serious events associated with dysrhythmia were reported with varying incidence within 42 days of quinolone administration. The crude rate of palpitation did not change significantly over that time for ciprofloxacin, ofloxacin and norfloxacin: CRR 0.83 (95% CI 0.02 to 6.86), 2.00 (95% CI 0.19 to 12.20) and 4.99 (95% CI 0.06 to 391.94), respectively. Syncope and tachycardia were also reported for ofloxacin [CRR 9.99 (95% CI 0.52 to 589.49 for both events)] and ciprofloxacin [1.0 (95% CI 0.02, 8.92)] and 2.50 (95% CI 0.04, 47.96) for syncope and tachycardia, respectively]. CONCLUSION: It cannot be ruled out that some rare hepatic and dysrhythmic events associated with quinolones may be drug related. The primary purpose of PEM is signal generation. Compared with the other quinolones, ciprofloxacin was associated with the highest number of reports of dysrhythmic cardiovascular events occurring within 42 days of administration. This requires further investigation by other types of epidemiological study.

Adult↗
PubMed1999

A comparison of the use, effectiveness and safety of bezafibrate, gemfibrozil and simvastatin in normal clinical practice using the New Zealand Intensive Medicines Monitoring Programme (IMMP).

AIMS: Because of the importance of treating dyslipidaemia in the prevention of ischaemic heart disease and because patient selection criteria and outcomes in clinical trials do not necessarily reflect what happens in normal clinical practice, we compared outcomes from bezafibrate, gemfibrozil and simvastatin therapy under conditions of normal use. METHODS: A random sample of 200 patients was selected from the New Zealand Intensive Medicines Monitoring Programme's (IMMP) patient cohorts for each drug. Questionnaires sent to prescribers requested information on indications, risk factors for ischaemic heart disease, lipid profiles with changes during treatment and reasons for stopping therapy. RESULTS: 80% of prescribers replied and 83% of these contained useful information. The three groups were similar for age, sex and geographical region, but significantly more patients on bezafibrate had diabetes and/or hypertension than those on gemfibrozil or simvastatin. After treatment and taking the initial measure into account, the changes in serum lipid values were consistent with those generally observed, but with gemfibrozil being significantly less effective than expected. More patients (15.8%S) stopped gemfibrozil because of an inadequate response compared with bezafibrate (5.4%) and simvastatin (1.6%). Gemfibrozil treatment was also withdrawn significantly more frequently due to a possible adverse reaction compared with the other two drugs. CONCLUSIONS: In normal clinical practice in New Zealand gemfibrozil appears less effective and more frequently causes adverse effects leading to withdrawal of treatment than either bezafibrate or simvastatin.

Bezafibrate↗
PubMed1997

Colonoscopic miss rates of adenomas determined by back-to-back colonoscopies.

BACKGROUND & AIMS: The miss rate of colonoscopy for neoplasms is poorly understood. The aim of this study was to determine the miss rate of colonoscopy by same day back-to-back colonoscopy. METHODS: Two consecutive same day colonoscopies were performed in 183 patients. The patients were randomized to undergo the second colonoscopy by the same or a different endoscopist and in the same or different position. RESULTS: The overall miss rate for adenomas was 24%, 27% for adenomas < or = 5 mm, 13% for adenomas 6-9 mm, and 6% for adenomas > or = 1 cm. Patients with two or more adenomas at the first examination were more likely than patients with no or one adenoma detected at the first examination to have one or more adenomas at the second examination (odds ratio, 3.3; 95% confidence interval, 1.69-6.46). Right colon adenomas were missed more often (27%) than left colon adenomas (21%), but the difference was not significant. There was evidence of variation in sensitivity between endoscopists, but significant miss rates for small adenomas were found among essentially all endoscopists. CONCLUSIONS: Using current colonoscopic technology, there are significant miss rates for adenomas < 1 cm even with meticulous colonoscopy. Miss rates are low for adenomas > or = 1 cm. The results suggest the need for improvements in colonoscopic technology.

Adenoma↗
PubMed1994

The prescribing and adverse reactions of nonsteroidal antiinflammatory drugs in general practice: a Dunedin study.

AIMS: The aims of this study were to describe the prescribing of nonsteroidal antiinflammatory drugs (NSAIDs) by some general practitioners and to assess the information recorded on computer records on their use in individual patients so that techniques could be developed for a broader investigation of the topic in general practice. METHODS: All prescribing and consulting data from five Dunedin practices was reviewed for a 6 month period. From all consultations generating a prescription for NSAIDs, data was collected relating to the name of the drug, dosage, strength and length of treatment and patient demographic and morbidity details. Recorded adverse drug reactions were classified into six groups and four age groups were used for the analysis. RESULTS: Prescriptions for NSAIDs accounted for 2.6% of all items prescribed. Diclofenac was the most commonly prescribed NSAID, for most conditions, but menstrual problems were more likely to be treated with mefenamic acid. Coprescription of possibly contraindicated medications (usually antihypertensive medicines) occurred for 20.8% of patients. Gastric adverse reactions were reported in 3% of cases while 0.9% of prescriptions resulted in no change in condition, leading to a change in therapy. Aspirin, fenbufen, ketoprofen, sulindac and flurbiprofen were never prescribed for patients under 20 years old. CONCLUSION: Routinely recorded patient and prescribing information from general practice permits an assessment of the use of NSAIDs which includes the conditions for which they are prescribed, the total numbers prescribed, concurrent medications prescribed and their recorded adverse effects. This is not possible from any other source. Data from clinical trials provides an incomplete assessment of the use of these medications in general practice.

Adult↗
PubMed1994

Diabetic gastroparesis. What to do when gastric emptying is delayed.

Diagnostic evidence or symptoms of gastroparesis develop in about 20% to 30% of patients with long-standing diabetes. Diabetic gastroparesis is likely caused by autonomic neuropathy involving the nerves that regulate gastric motor function. The following are necessary for diagnosis: thorough history taking and physical examination to eliminate factors that might further delay gastric emptying; esophagogastroduodenoscopy or barium contrast studies to exclude structural abnormalities; and a radionuclide gastric emptying study. The three main agents available for therapy in the United States are metoclopramide (Maxolon, Octamide, Reglan), erythromycin, and cisapride (Propulsid). All have been shown to offer benefit in improving gastric emptying and symptoms, although use of metoclopramide is limited by a significant incidence of side effects. Surgical intervention should be avoided if possible.

Diabetic Neuropathies↗
PubMed1992

General practitioners' views on the role of the community pharmacist.

AIM: to determine the views of general practitioners on the roles and activities of community pharmacists. METHOD: the views of 137 general practitioners in Otago and Southland were canvassed by postal questionnaire. RESULTS: one hundred and three completed questionnaires were returned. All of the general practitioners reported that their professional contact with pharmacists was useful. Seventy-five percent expressed a desire for greater cooperation. Nearly all respondents (99%) accepted that pharmacists have a role in screening prescriptions for possible problems and preparing and dispensing medicines. They also accepted that pharmacists were capable of treating and advising in the management of minor illnesses. Providing drug information to general practitioners, information about previously diagnosed conditions to patients, and advice on personal and home hygiene were less widely accepted activities. The majority indicated that they considered it inappropriate for pharmacists to undertake screening programmes (blood pressure (70.6%), cholesterol (70.6%), glucose (60.8%), haemoglobin (72.5%)). Younger general practitioners objected more often than older general practitioners to reclassification of Acetopt eye drops from prescription only to availability through pharmacies (p < 0.05). Female general practitioners were more often in favour of reclassification of Gyno-Daktarin than their male colleagues (p < 0.05). CONCLUSION: this study shows that general practitioners accept several aspects of the current role of pharmacists in providing primary health care. However, there is room for improved communication between general practitioners and pharmacists to ensure optimum patient care.

Adult↗
PubMed1991

Technical aspects of the use of the Russell-Taylor reconstruction nail.

The introduction of the reconstruction nail has broadened the indications for the intramedullary fixation of difficult femoral fractures. The operative technique is, however, complicated. Some technical difficulties encountered during its use are presented, together with guidance to allow these problems to be avoided.

Adult↗
PubMed1991

Knowledgeable non-compliance with prescribed drugs in elderly subjects--a study with particular reference to non-steroidal anti-inflammatory and antidepressant drugs.

Knowledgeable non-compliance with non-steroidal anti-inflammatory drugs (NSAIDs) and antidepressant drugs was investigated in a community-based sample of elderly people. Everyone 70 years and over living in a defined area and taking one of the above drugs, and at least one other prophylactic or symptomatic drug, was studied. Non-steroidal anti-inflammatory drugs and antidepressant drugs are commonly regarded as symptomatic only and knowledgeable non-compliance is consequently high. They are also regarded as less important than drugs which produce no immediate relief of symptoms but which the patient recognizes as needing to be taken regularly to maintain health. In our study, compliance with non-steroidal anti-inflammatory drugs and antidepressant drugs was highest in those who were compliant with a prophylactic drug and were also taking a symptomatic drug. The greater the number of tablets the patient was taking the more likely he or she was to be compliant with the NSAID. Compliance with NSAIDs and antidepressant drugs requires clear label instructions and the patient knowing the purpose of the medication.

Aged↗
PubMed1990

Medication use in nine year olds: types of medicines used and recall of advice given.

Use of medications was investigated in 819 nine year old children living in Dunedin. Twenty-four percent of the cohort (199 children) were given medications during the week prior to interview, mainly on prescription (68%). The majority of medicines used were said to be for respiratory illnesses and oral antibiotics represented a high proportion of prescribed medicines. Most medicines were obtained through a pharmacy (91%), and side effects were noted by nine percent of those taking medications. Some counselling was recalled with 70% of items although, as recalled by the parent, less than 25% of medicines obtained from pharmacies were dispensed or sold with any advice or instruction. The prescriber must ensure that adequate information is provided for the patient. Pharmacists may reinforce this information and provide additional advice on optimum methods of administration. It is debatable whether antibiotics should be used to the extent indicated by this study.

Child↗
PubMed1990

Treatment of unstable intertrochanteric fractures of the femur: a prospective trial comparing anatomical reduction and valgus osteotomy.

A series of 100 consecutive patients with unstable intertrochanteric fractures were treated by compression hip screw fixation; 55 patients had an anatomical reduction (Group 1) and 45 patients a Sarmiento osteotomy and valgus reduction (Group 2). Group 1 spent an average of 10 days less in hospital than Group 2 (21 days compared with 31 days) (P less than 0.02). They also had a greater chance of returning to their pre-injury accommodation and of achieving their pre-injury walking capability. Radiological failure of fracture fixation, with varus angulation of the femoral head by cutting out of the screw, was seen seven times in Group 1 but only once in Group 2. Anatomical reduction provides better clinical results than valgus osteotomy in the patient with an unstable intertrochanteric fracture stabilized by a compression hip screw. The capacity for failure of fracture fixation is greater, however, in the former. Valgus osteotomy provides a simple means of securing a stable reduction of the fracture which cannot be satisfactorily reduced by closed means.

Aged↗
PubMed1990

First-choice antihypertensive drug use in the Glasgow Blood Pressure Clinic.

The evolution of antihypertensive drug use in the Glasgow Blood Pressure Clinic between 1969 and 1986 was determined, from computerized data, by extracting percentages of new patients prescribed different drugs at their first clinic visit. Prescribing of adrenergic neuron blockers and centrally acting drugs (methyldopa and clonidine) was common in the early years but declined rapidly until, after 1975 and 1980, respectively, it remained at 10% or less. Diuretics, mainly thiazides, were prescribed for 20% of patients in 1969 to a peak of 55% in 1980. beta-Blockers were first used during the early 1970s and their use peaked in 1980, when they were prescribed for over 60% of new patients. They remained a first-choice treatment in more than 40% of patients. Calcium channel blockers were first used in 1980 and by 1986 were prescribed for 15% of new patients. Angiotensin-converting enzyme inhibitors were used from 1982 and in 1986 were prescribed for 7% of new patients. These two classes of drugs are more expensive than older drugs. However, because of their low usage, this did not greatly influence treatment costs up to 1986, as beta-blockers and thiazides remained widely used.

Adrenergic beta-Antagonists↗
PubMed1989

Variability in the elimination of mianserin in elderly patients.

1. Two studies of the elimination of mianserin are reported. 2. In the first study, the oral clearance of mianserin was measured in 15 elderly patients at steady state. In a sub-group of eight patients who completed studies at two different doses there was evidence of enhanced oral clearance at the higher dose. 3. In the second study, the elimination half-life was estimated in 12 patients who were observed to have disproportionately high mianserin concentrations with respect to dose. All had half-lives greater than or equal to 2.5 days with a mean of 6 +/- 2.8 (s.d.) days. In six of the patients the profile of elimination was suggestive of saturable elimination. 4. The sparteine oxidation status was measured in seven of the patients showing slow mianserin elimination. Only one was a 'poor oxidiser' of sparteine, suggesting no concordance with this phenotype. 5. It is concluded that there is marked variability in the elimination of mianserin in elderly patients.

Aged↗
PubMed1989

Treatment of periscaphoid osteoarthritis by Silastic scaphoid implant.

Periscaphoid osteoarthritis may arise de novo or as a sequel of an established non-union of a scaphoid fracture. The treatment of resultant pain and disability often presents a difficult problem since internal fixation and/or bone grafting of the pseudoarthrosis may fail to relieve the symptoms due to degenerative change. Many methods of alleviating these symptoms have been suggested in the past. We have reviewed the experience of the Windsor Orthopaedic group in the use of Silastic scaphoid implants.

Adult↗
PubMed1989

[Respiratory function in idiopathic scoliosis in adolescents treated by Harrington instrumentation with or without sublaminar segmental wiring].

The forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC) of 40 adolescents with idiopathic scoliosis were studied before and after surgery. The values obtained are expressed as percentages of the predicted normal. Twenty-one patients underwent surgical correction of the curve with Harrington rods followed by cast and brace immobilisation for one and a half years (Group A). In the other 19 patients the Harrington rod was contoured in the sagittal plane and supplemented with segmented sublaminar wires to allow rapid post-operative mobilisation free of any orthosis (Group B). A negative correlation was found pre-operatively between the magnitude of the curve and the FEV1 and FVC. The post-operative pulmonary function showed no statistically significant improvement. Contouring the Harrington rod to improve kyphosis in Group B did not affect the outcome.

Adolescent↗
PubMed1989

[Surgical treatment of scoliosis using Harrington instrumentation and arthrodesis. A comparison of 2 series with and without sublaminar segmental wiring].

The use of sublaminar segmental wires to enhance the stability of Harrington instrumentation was assessed in a review of our experience in the treatment of scoliosis over the last 6 years. Thirty patients were treated by spinal fusion, Harrington instrumentation and a prolonged postoperative period of immobilisation, initially in a plaster cast and then in a brace (Group 1). A further 29 patients have been treated by augmenting the Harrington instrumentation with sublaminar segmental wires (Group 2). Post-operatively, this group was left free of any brace or cast and early mobilisation was allowed. We observed no neurological complication in either group. The blood loss and the duration of the operation were greater in Group 2, but the period of hospitalisation and time to return to school has been markedly reduced. There has been no significant difference in the degree of correction of the scoliosis between the groups, but the improvement in kyphosis was greater with the use of sublaminar wires. There were no pseudoarthroses in either group during a minimum follow up of 18 months.

Adolescent↗