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Biomedical subjects

S Stephenson

Publications and source records attributed to S Stephenson.

At least 19 recordsLinked to original sources
PubMed2006

Eye movements coordinated with steering benefit performance even when vision is denied.

When driving along a winding road, eye movements and steering are tightly linked. When approaching a bend, the driver looks across to the inside kerb (the tangent point) some time before turning the steering wheel. All drivers we have tested show this optimal coordination, without which driving is impaired. An intriguing question is how much of the benefit for steering arises just from moving the eyes in this coordinated way (ahead of steering and in the same direction), and how much from the visual information that the eyes move to acquire, in this instance the foveated tangent point. This can be answered by dissociating the two, by reducing visibility of the road ahead (and crucially of the tangent point) to a level at which drivers might or might not choose to move their eyes but, if they do, will not gain the information they seek. Twenty subjects repeatedly drove a simulated stage of the World Rally Championship. With full visibility, they exhibited the usual coordination of eye movements and steering. Subsequently, visibility was reduced on the left hand side. Drivers who persisted in making eye movements coordinated with steering to the left, despite the fact that they could no longer see the tangent point on that side, performed better than drivers who under the identical conditions did not look to the left. This confirms that the making of coordinated eye movements itself benefits steering, even when the eye movements do not yield the visual information sought.

Adult↗
PubMed2006

Accuracy of injury coding under ICD-9 for New Zealand public hospital discharges.

OBJECTIVE: To determine the level of accuracy in coding for injury principal diagnosis and the first external cause code for public hospital discharges in New Zealand and determine how these levels vary by hospital size. METHOD: A simple random sample of 1800 discharges was selected from the period 1996-98 inclusive. Records were obtained from hospitals and an accredited coder coded the discharge independently of the codes already recorded in the national database. RESULTS: Five percent of the principal diagnoses, 18% of the first four digits of the E-codes, and 8% of the location codes (5th digit of the E-code), were incorrect. There were no substantive differences in the level of incorrect coding between large and small hospitals. CONCLUSIONS: Users of New Zealand public hospital discharge data can have a high degree of confidence in the injury diagnoses coded under ICD-9-CM-A. A similar degree of confidence is warranted for E-coding at the group level (for example, fall), but not, in general, at higher levels of specificity (for example, type of fall). For those countries continuing to use ICD-9 the study provides insight into potential problems of coding and thus guidance on where the focus of coder training should be placed. For those countries that have historical data coded according to ICD-9 it suggests that some specific injury and external cause incidence estimates may need to be treated with more caution.

Abbreviated Injury Scale↗
PubMed2005

A history of total mercury in edible muscle of fish from lakes in northern Canada.

Subsistence fishing has been an important source of food for Native People in northern Canada since prehistoric time. Measurements of the levels of mercury in edible muscle of northern fish have been undertaken for over three decades in efforts to evaluate the risks of consuming northern fish. This report summarizes the data obtained from 7974 fish of 25 species from sites distributed from the Yukon to Labrador. The most abundant species were lake trout, lake whitefish, arctic char, walleye, northern pike and burbot. The question being asked was essentially "Are the fish safe to eat?" The results were used to support decisions on fishing and consumption of fish. They were sorted in several ways, into concentration ranges corresponding to human consumption guidelines, into political jurisdictions and into types of bedrock geology. Overall walleye, northern pike and lake trout, usually exceeded the subsistence consumption guideline of 0.2 microg g-1 total mercury and often exceeded the higher guideline of 0.5 microg g-1 total mercury for commercial sales of fish. Mercury in burbot, another facultative predator, was often lower but several still exceeding a guideline. Arctic char collections were mostly from anadromous populations and these had very low levels of mercury, presumably reflecting marine food sources. Lake whitefish were among the cleanest fish examined with 69 of 81 collections falling in the lowest range. Most collections were from sites in sedimentary rock. However a few sites were in metamorphic, intrusive or volcanic rocks and these, taken together, tended to have a higher proportion of sites in the higher ranges of mercury. These results indicate a widespread problem with mercury in subsistence fisheries for predator species of fish with the problem being most problematic for Nunavut.

Animals↗
PubMed2005

Duodenal obstruction by gallstones (Bouveret's syndrome): a review of the literature.

Bouveret's syndrome, first described in 1896, is gastric obstruction by a gallstone following a cholecystoduodenal fistula. Endoscopy is the mainstay of diagnosis, but radiographic examination such as upper gastrointestinal contrast series and abdominal radiography can also contribute to the diagnosis. Diagnosis by computed tomography and ultrasonography has also been described. The syndrome can be diagnosed and treated endoscopically, with stone extraction or mechanical lithotripsy. Extracorporeal shockwave lithotripsy has also been used successfully. Surgery is required in over 90% of cases, with mortality rates ranging from 19% to 24%. One-stage and two-stage procedures have been described, including enterolithotomy, cholecystectomy, and fistula repair, no convincing data are available to show which of these two approaches provides a better outcome. Although the condition is rare, Bouveret's syndrome should be considered in elderly patients with a history of chronic cholecystitis who present with pain, vomiting or haematemesis.

Age Factors↗
PubMed2005

Comparison of injury case fatality rates in the United States and New Zealand.

OBJECTIVE: To compare injury case fatality rates in the United States (US) with New Zealand (NZ) to guide future information collection, research, and evaluation. DESIGN: Using NZ (1992-96) and US (1996-98) mortality censuses, NZ national 1992-96 hospital discharge censuses, and US 1996-98 National Hospital Discharge Survey data, the authors compared case fatality rates by mechanism and intent of injury and age group. The analysis was restricted to severe injuries (AIS> or =3). SUBJECTS: NZ (1992-96) and US (1996-98) populations. MAIN OUTCOME MEASURES: Ratio of case fatality rates in NZ versus the US (RCFR(NZ:US)). RESULTS: Overall, among cases meeting the study criteria, unintentional injuries were 1.57 times more likely fatal in NZ and intentional assault injuries were 1.14 times more likely to be fatal in the US. Firearms were involved in 50% of US assaults versus 8% of NZ assaults. By mechanism, cutting/piercing injuries were 1.86, firearm injuries were 1.41, and motor vehicle injuries were 1.44 times more to be likely fatal in NZ. Natural/environmental injuries (RCFR(NZ:US) = 0.57), unintentional poisonings (RCFR(NZ:US) = 0.26), and unintentional suffocations (RCFR(NZ:US) = 0.67) were significantly more likely to be fatal in the US. CONCLUSIONS: Possible reasons for the observed results include: differences in geography and proportion of population in rural areas, trauma system differences, road design and vehicle types, seat belt use, larger role of firearms in US assaults, coding practices, policies, and environmental factors. Disparities evoke hypotheses to test in future research that will guide priority setting and intervention.

Accidents, Traffic↗
PubMed2004

Diagnosis based injury severity scaling: investigation of a method using Australian and New Zealand hospitalisations.

OBJECTIVE: To assess the performance of the International Classification of Diseases (ICD) based injury severity score, ICISS, when applied to two versions of the 10th edition of ICD, ICD-10 and ICD-10-AM. DESIGN: ICISS was assessed on its ability to predict threat to life using logistic regression modelling. Models used ICISS and age as predictors and survival as the outcome. SETTING: Australia and New Zealand. Patients or SUBJECTS: Hospitalisations with an ICD-10-AM principal diagnosis in the range S00-T89 from 1 July 1999 to 30 June 2001 (Australia) or 1 July 1999 to 31 December 2001 (New Zealand). INTERVENTIONS: None. MAIN OUTCOME MEASURES: The models were assessed in terms of their discrimination, measured by the concordance score, and calibration, measured using calibration curves and the Hosmer-Lemeshow statistic. RESULTS: 523 633 Australian and 124 767 New Zealand hospitalisations were selected, including 7230 and 1565 deaths respectively. Discrimination was high in all the fitted models with concordance scores of 0.885 to 0.910. Calibration results were also promising with all calibration curves being close to linear, though ICISS appeared to underestimate mortality somewhat for cases with an ICISS score less than 0.6. Overall ICISS performed better when applied to the Australian than the New Zealand hospitalisations. Australian and New Zealand hospitalisations were very similar. ICISS was also only a little more successful when ICD-10-AM rather than mapped ICD-10 was used. CONCLUSIONS: ICISS appears to be a reasonable way to estimate severity for databases using ICD-10 or ICD-10-AM. It is also likely to work well for other clinical variants of ICD-10.

Adolescent↗
PubMed2004

Prevalence of chronic renal failure in the diabetic population at the University Hospital of the West Indies.

The prevalence of chronic renal failure (CRF) in 460 patients with diabetes mellitus attending the diabetic outpatient clinic at the University Hospital of the West Indies in Jamaica was determined from a review of medical records. The prevalence of CRF was 10% (39/386) in the diabetic clinic population. Significant positive associations with CRF were found with male gender (20/98, 20% vs 19/287, 7%; odds ratio (OR), 3.24; p = 0.001); age 60 years and older (22/162; 14% vs 17/221, 8%; OR, 2.01; p = 0.04); fasting blood glucose concentrations exceeding 8.0 mmol/L (22/162, 13% vs 12/182, 7%; OR, 2.08; p = 0.05); the presence of significant proteinuria as a marker for outcome (13/39, 33% vs 48/346, 14%; OR, 3.60; p = 0.02) and peripheral vascular disease (6/20, 30% vs 139/386, 10%; OR, 4.75; p = 0.005). The prevalence of CRF did not differ significantly between patients with Type 1 and Type 2 diabetes mellitus. Also, the presence of CRF was not significantly associated with duration of diabetes mellitus, type of hypoglycaemic agents used, or history of hypertension. However, the presence of persistent proteinuria was significantly associated with duration of diabetes mellitus exceeding five years (46/255, 17% vs 11/149, 7%; OR, 2.52; p = 0.005) and a history of hypertension (41/235, 17% vs 20/198, 10%; OR, 1.88; p = 0.03) but not with age or gender. This study emphasizes the need to evaluate patients with diabetes mellitus for renal impairment so that intervention strategies may be adopted early to delay progression to endstage renal disease.

Adolescent↗
PubMed2003

Dental and maxillofacial injuries among older New Zealanders during the 1990s.

Not only is the number of older people increasing in New Zealand, but a greater number of them are keeping their own teeth, with predictable consequences for the costs of treating (and rehabilitating) dental and maxillofacial trauma in that group. The aim of the study was to describe the occurrence of dental and maxillofacial trauma involving New Zealanders aged 65 and over during the 1990s. The investigation was a secondary analysis of routinely collected, national-level compensation and hospital treatment data. The analysis showed that: (1) there was an increase in the rate and absolute number of injuries among older people; (2) the dental trauma rate was highest among males in the youngest age group, while the facial fracture rate was highest among older females; and (3) there was a general increase in the contribution of falls to the occurrence of trauma. Measures which aim to reduce the occurrence of falls among older people will also reduce the oral and maxillofacial trauma rate in that age group.

Accidental Falls↗
PubMed2003

Missing cyclists.

OBJECTIVES: (1) For crashes on a public road, to compare serious cyclist crashes involving a motor vehicle with cyclist crashes not involving a motor vehicle, in terms of threat to life and length of stay in hospital. (2) To determine the proportion of all serious crashes involving cyclists on public roads which are recorded by the police. (3) To determine the degree to which under-reporting of serious crashes involving cyclists and motor vehicles on public roads is associated with various demographic, environmental, and injury factors. STUDY DESIGN: Records for the period 1995-99, of cyclists seriously injured on a public road and hospitalised were linked to the traffic crash report (TCR) database maintained by Land Transport Safety Authority (LTSA). RESULTS: Of the 2925 cyclist crashes on public roads, only 652 (22%) could be linked to a TCR. Of the crashes involving motor vehicles (n = 1033), only 562 (54%) could be linked to the LTSA database. Age, ethnicity, injury severity, and cumulative length of stay were the only variables that predicted whether hospitalised cycle crash cases were more likely to have a corresponding TCR. There were substantial numbers of cyclist only crashes which typically are not captured in the TCR database. Nine percent of these resulted in serious or worse injury (that is, International Classification of Diseases/abbreviated injury scale score of 3+) and 7% resulted in hospital stays greater than seven days. CONCLUSION: Greater effort and precision needs to be applied to routinely document the burden of cyclist crashes, especially cyclist only crashes.

Abbreviated Injury Scale↗
PubMed2002

Serious facial fractures in New Zealand from 1979 to 1998.

We present data on the incidence, aetiology, age, sex and ethnic distribution of facial fractures in New Zealand for the 20-year period from 1979-1998. Most facial fractures (78.9%) occurred in males with a rate of 65.5/100,000, person-years compared with 21% in females with an incidence of 17/100,000. While the injury rate peaked in males between the ages of 20-24 years (200/100,000), it peaked between 15-19 years (34.7/100,000) in females. The most common causes of facial fracture in both genders were assault (14/100,000) and being unintentionally struck by an object or person (9.5/100,000) which is consistent with similar data from South Africa and the USA. The rates of fracture in Maori (68.1/100,000) were approximately twice those of Pacific Islanders (37/100,000) or other ethnic groups (34.2/100,000).

Accidents, Traffic↗
PubMed2002

Traps for the unwary in estimating person based injury incidence using hospital discharge data.

BACKGROUND: Injuries resulting in admission to hospital provide an important basis for determining priorities, emerging issues, and trends in injury. There are, however, a number of important issues to be considered in estimating person based injury incidence using such data. Failure to consider these could result in significant overestimates of incidence and incorrect conclusions about trends. AIM: To demonstrate the degree to which estimates of the incidence of person based injury requiring hospital inpatient treatment vary depending on how one operationally defines an injury, and whether or not day patients, readmissions, and injury due to medical procedures are included. METHOD: The source of data for this study was New Zealand's National Minimum Dataset. The primary analyses were of a dataset of all 1989-98 discharges from public hospital who had an external cause of injury and poisoning code assigned to them. RESULTS: The results show that estimates of the incidence of person based injury vary significantly depending on how one operationally defines an injury, and whether day patients, readmissions, and injury due to medical procedures are included. Moreover the effects vary significantly by pathology and over time. CONCLUSIONS: (1) Those using New Zealand hospital discharge data for determining the incidence of injury should: (a) select cases which meet the following criteria: principal diagnosis injury only cases, patients with day stay of one day or more, and first admissions only, (b) note in their reporting that the measure is an estimate and could be as high as a 3% overestimate. (2) Other countries with similar data should investigate the merit of adopting a similar approach. (3) That the International Collaborative Effort on Injury Statistics review all diagnoses within International Classification of Diseases 9th and 10th revisions with a view to reaching consensus on an operational definition of an injury.

Age Distribution↗
PubMed2001

Evaluation of coronary risk factors in patients with heterozygous familial hypercholesterolemia.

Age at onset of clinically manifested coronary artery disease (CAD) varies widely among patients with familial hypercholesterolemia (FH). A number of factors in addition to high low-density lipoprotein cholesterol (LDL) have been suggested as predictors of risk among patients with FH, but a comprehensive examination of their utility is lacking. We therefore measured plasma lipids, carotid intima-medial thickness, and a variety of coronary risk factors in 262 patients with FH > or = 30 years old (68 of whom had premature CAD). Age (p < 0.0001) and gender were the most important determinants of premature CAD risk, with men having 5.64 times the risk of women (p < 0.0001). In addition, cigarette smoking (odds ratio [OR] 2.71, p = 0.026), smaller LDL as determined by the LDL cholesterol/LDL apolipoprotein B ratio (OR 2.60, p = 0.014), and white blood cell count (p = 0.014) were also statistically significant risk factors. Lipoprotein(a) and the presence of xanthoma were associated with risk only in very early coronary cases. After correction for age, carotid intima-media thickness was not associated with CAD risk. Insulin, fibrinogen, homocysteine, plasma C-reactive protein, and the angiotensin-converting enzyme insertion/deletion polymorphism were unrelated to risk in this cohort. These results provide little justification for extensive investigation of risk factors among patients with FH, at least for the risk factors examined here. Rather, the inherent high LDL cholesterol of these patients should be the focus of preventive efforts. The novel finding of increased risk with smaller LDL may prove useful but needs further confirmation.

Adult↗
PubMed2001

Frequency of the R3500Q mutation of the apolipoprotein B-100 gene in a sample screened clinically for familial hypercholesterolemia in Hungary.

Familial hypercholesterolemia (FH) and familial defective apolipoprotein B-100 (FDB) cause early onset of coronary heart diseases (CHD). According to the recommendations of the international MEDPED program, we tried to find FH cases. We analyzed 73 FH probands and their 304 first-degree relatives. A total of 39 probands were found from the 21000 subjects screened (1:538) from family doctors' registers recording all citizens, while the remaining 34 were derived from screened patients from lipid clinics. In our FH probands, four cases of FDB (R3500Q mutation) were diagnosed with allele-specific PCR, and the mutation was also detectable in five cases out of seven living family members. In the remaining 69 FH families, 156 people were diagnosed clinically with FH, and 31.8% of the males (against 13% of the not clinically diagnosed FH males, P<0.01), and 32.4% of the females (against 13.5% of the not clinically diagnosed FH females, P<0.01) suffered from early onset CHD. The plasma total cholesterol level of the FDB patients, especially in the younger patients, was very close to normal values. Therefore, the FDB patients seem to be under-represented in this type of survey. Because FDB is one of the independent causes of early onset CHD, the R3500Q mutation should be considered in families with a high frequency of cardiovascular diseases.

Adolescent↗
PubMed2001

Impact of graduated driver licensing restrictions on crashes involving young drivers in New Zealand.

OBJECTIVE: To determine the impact on young driver crashes of the three main driving restrictions in the New Zealand graduated driver licensing (GDL) system: night-time curfew, no carrying of young passengers, and a blood alcohol limit of 30 mg/100 ml. METHOD: The database for this study was created by linking police crash reports to hospital inpatient records (1980-95). Multivariate logistic regression was used to compare car crashes involving a young driver licensed before GDL (n=2,252) with those who held a restricted graduated licence (n=980) and with those who held a full graduated licence (n=1,273), for each of the main driving restrictions. RESULTS: Compared with the pre-GDL group, the restricted licence drivers had fewer crashes at night (p=0.003), fewer involving passengers of all ages (p=0.018), and fewer where alcohol was suspected (p=0.034), but not fewer involving young casualties (p=0.980). Compared with the pre-GDL drivers, those with the full graduated licence had fewer night crashes (p=0.042) but did not differ significantly for any of the other factors examined. CONCLUSION: These results suggest that some of the GDL restrictions, especially the night-time curfew, have contributed to a reduction in serious crashes involving young drivers.

Accidents, Traffic↗
PubMed2000

Selective omission of the donor cross-match before renal transplantation: efficacy, safety and effects on cold storage time.

BACKGROUND: A donor lymphocyte cross-match (XM) test performed before renal transplantation is considered mandatory but may delay the transplant and increase the cold storage time. With careful documentation of sensitizing events and with knowledge of previous antibody screening results, it is often possible to predict the XM result for a given donor HLA mismatch. In this study, a policy was adopted of omitting the pretransplant XM in patients in whom a negative result was predicted with absolute confidence. METHODS: Recipients were selected for cadaveric donor kidney transplantation using a computer algorithm based on HLA match, sensitization status, time on the waiting list and donor and recipient age. The immediate pretransplant cross-match test was omitted in non-sensitized recipients and in sensitized recipients where antibody specificities were precisely defined and not against donor HLA. RESULTS: From October 1997 to May 1999, 53 of 96 (55%) consecutive cadaveric kidney donor transplants were performed without a pretransplant XM. In all cases, a negative donor HLA-specific antibody XM was confirmed after transplantation. Omission of the pre-transplant XM was associated with a significant reduction in cold ischemic time (15.0 hr vs. 18.2 hr, P=0.01) and a reduced incidence of delayed graft function (13% vs. 33%, P=0.03). However, there was no difference in transplant outcome at 1 year. CONCLUSION: Rigorous attention to priming events together with careful antibody screening allows the pre-transplant XM test to be safely omitted in approximately half the patients awaiting renal transplantation. This policy allows a modest reduction in cold ischemia time, but it remains to be seen whether this is of clinical benefit.

Adult↗
PubMed2000

The use of a hydrophobic matrix for the sustained release of a highly water soluble drug.

An experimental investigation into the use of a hydrophobic matrix to control the release of a highly water soluble drug was undertaken. Matrices consisting of hydrogenated vegetable oil and calcium sulfate with a 4% drug loading showed a sustained-release profile of up to 24 hr. The release mechanism from such matrices seemed to obey both root time kinetics and first-order behavior. Investigations showed that the effect of geometry had a significant effect on the drug release rate.

Algorithms↗
PubMed1999

Primordial prevention of cardiovascular disease through applied genetics.

Primordial prevention might be considered prevention of the development of disease at its earliest stages or early intervention on risk factors to eliminate increased risk in the first place. In this review we consider how knowledge of genetic causes of early cardiovascular disease can lead to directed screening and better treatment of high risk individuals. While gene therapy would be the most "primordial" approach to prevention of some diseases such as familial hypercholesterolemia, its practical application remains on the horizon. Nevertheless, there is much we can do now to prevent early deaths in genetically high risk patients. Here we consider epidemiology as the parent discipline for applied genetics and as integral to primordial prevention. With new knowledge of special susceptibility and new understanding of the interaction of genetics and exposures, prevention of individual high-risk in the first place is realizable. We summarize here the known and candidate genes influencing atherosclerosis, hypertension, and thrombosis; their diagnosis; and some useful preventive approaches. MEDPED, an international scheme for detection of risk in medical pedigrees, is described, along with the cost and social implications of its application as a preventive strategy.

Cardiovascular Diseases↗