An epidemiological model for externally sourced vector-borne viruses applied to Bean yellow mosaic virus in lupin crops in a Mediterranean-type environment.

A hybrid mechanistic/statistical model was developed to predict vector activity and epidemics of vector-borne viruses spreading from external virus sources to an adjacent crop. The pathosystem tested was Bean yellow mosaic virus (BYMV) spreading from annually self-regenerating, legume-based pastures to adjacent crops of narrow-leafed lupin (Lupinus angustifolius) in the winter-spring growing season in a region with a Mediterranean-type environment where the virus persists over summer within dormant seed of annual clovers. The model uses a combination of daily rainfall and mean temperature during late summer and early fall to drive aphid population increase, migration of aphids from pasture to lupin crops, and the spread of BYMV. The model predicted time of arrival of aphid vectors and resulting BYMV spread successfully for seven of eight datasets from 2 years of field observations at four sites representing different rainfall and geographic zones of the southwestern Australian grainbelt. Sensitivity analysis was performed to determine the relative importance of the main parameters that describe the pathosystem. The hybrid mechanistic/statistical approach used created a flexible analytical tool for vector-mediated plant pathosystems that made useful predictions even when field data were not available for some components of the system.

Computed tomography versus intravenous urography in diagnosis of acute flank pain from urolithiasis: a randomized study comparing imaging costs and radiation dose.

The equivalent sensitivity of non-contrast computed tomography (NCCT) and intravenous urography (IVU) in the diagnosis of suspected ureteric colic has been established. Approximately 50% of patients with suspected ureteric colic do not have a nephro-urological cause for pain. Because many such patients require further imaging studies, NCCT may obviate the need for these studies and, in so doing, be more cost effective and involve less overall radiation exposure. The present study compares the total imaging cost and radiation dose of NCCT versus IVU in the diagnosis of acute flank pain. Two hundred and twenty-four patients (157 men; mean age 45 years; age range 19-79 years) with suspected renal colic were randomized either to NCCT or IVU. The number of additional diagnostic imaging studies, cost (IVU A$136; CTU A$173), radiation exposure and imaging times were compared. Of 119 (53%) patients with renal obstruction, 105 had no nephro-urological causes of pain. For 21 (20%) of these patients an alternative diagnosis was made at the initial imaging, 10 of which were significant. Of 118 IVU patients, 28 (24%) required 32 additional imaging tests to reach a diagnosis, whereas seven of 106 (6%) NCCT patients required seven additional imaging studies. The average total diagnostic imaging cost for the NCCT group was A$181.94 and A$175.46 for the IVU group (P < 0.43). Mean radiation dose to diagnosis was 5.00 mSv (NCCT) versus 3.50 mSv (IVU) (P < 0.001). Mean imaging time was 30 min (NCCT) versus 75 min (IVU) (P < 0.001). Diagnostic imaging costs were remarkably similar. Although NCCT involves a higher radiation dose than IVU, its advantages of faster diagnosis, the avoidance of additional diagnostic imaging tests and its ability to diagnose other causes makes it the study of choice for acute flank pain at Christchurch Hospital.

Variability within general practitioner prescribing over time.

AIMS: We have described intra-general practitioner (GP) prescribing variability over time in terms of volume, cost and average item cost of prescription items, within New Zealand general practice. METHODS: Longitudinal data over the financial years 1992-94 were studied for two GP samples. Prescription data for a regional sample of 305 GPs were obtained for the first six months (January to June) from the New Zealand pharmaceutical pricing office, Health Benefits Limited. Prescription data from a second national sample of 74 GPs were obtained from the PreMeC prescription analysis (PAS) database of GPs who had participated in three consecutive September to December prescription analyses. The coefficient of variation was used to measure the intra-GP variability over time in total prescription cost, volume of prescription items and average prescription item cost. RESULTS: The median intra-GP variability over time for the regional GP sample, based on reimbursement data, was 9% in total cost, 9% in total volume and 5% in average item cost. The median intra-GP variability in the national sample was very similar to the regional sample when based on reimbursement data, but when PAS data were used the variability was 16% in total cost, 17% in total volume and 8% average item cost. CONCLUSIONS: The year-on-year, intra-GP variability for cost was 9%, for volume 9-10% and for average item cost 5-6%. Pharmaceutical budget estimates should reflect year-to-year intra-GP prescribing variability of the order of 9%.

Living with high blood pressure.

This study was undertaken to explore the experience of people taking long-term antihypertensive medication. The study contributes to the understanding health professionals have of people with high blood pressure and the antihypertensive treatments they receive. Consideration was given to the full life context of people taking long-term antihypertensive medication and the health/medical culture in which people find themselves. A qualitative method of inquiry generated the descriptive data. Nineteen participants (four men and 15 women) were interviewed once, of which 16 were interviewed a second time. Data analysis involved extraction of concepts which in turn were clustered into themes. An organizing framework was constructed to integrate the six themes and 18 sub-themes. The framework represents the individual's experience as a sequence, starting broadly in the social context of her/his life, and narrowing down to the particulars of personal routine and patterns referring to living with hypertension and it's medication regimens. The final theme refers to the broader context of the health culture. A vast range of experiences were described by participants taking long-term antihypertensive medication. This accentuates the necessity for health professionals to address the uniqueness of the individual, and consider the context of a person's life when prescribing and monitoring medications for people with high blood pressure.

Vesicoureteric reflux in the newborn: relationship to fetal renal pelvic diameter.

There has been a low yield of primary vesicoureteric reflux (VUR) from screening the fetal urinary tract during obstetric sonography. We sought to determine whether changing the cut-off level of fetal renal pelvic diameter from 10 mm to 4 mm would improve the yield of VUR. In a prospective community-based study, a fetal renal pelvic diameter of 4 mm or more on a transverse view of the fetal renal hilum at obstetric sonography after 16 weeks' gestation was found in 426 fetuses from 9,800 consecutive pregnancies. After birth, renal sonography was performed on 386 of the 426 babies. Of the 386 babies, 264 (187 boys) had a voiding cystourethrogram (VCUG) at a mean age of 9 weeks. Primary VUR was detected in 33 (16 boys) of the 264 infants (13%), and secondary VUR in another 5 (2%). Only 5 of the 33 (15%) babies with primary VUR would have been detected if a cut-off point of 10 mm for fetal renal pelvic diameter had been used. The prevalence of reflux was similar at each cut-off level of antenatal renal pelvic diameter from 4 to 10 mm. Neither calyceal nor ureteric dilatation was helpful in differentiating those with from those without VUR. The postnatal renal sonogram did not distinguish whether reflux was present or not. More infants with primary VUR, particularly girls, were found by changing the cut-off point for fetal renal pelvic diameter from 10 mm to 4 mm, and performing a VCUG on all such infants even if the postnatal renal sonogram was normal. Of the 33 infants with primary VUR, 9 (27%, 5 boys) had an abnormal dimercaptosuccinic acid scan. Our findings support the screening of the obstetric population for a fetal renal pelvic diameter of 4 mm or more, and then investigating the infants for VUR after birth.

DMSA renal scans in adults with acute pyelonephritis.

The 99mTc-DMSA scan is accepted as the most sensitive imaging modality for detecting areas of renal parenchymal scarring. More recently the DMSA scan has also been shown to be of value in imaging areas of renal parenchymal involvement in both children and adults with acute pyelonephritis. We assessed the acute DMSA scan findings in a consecutive series of 81 patients hospitalized with acute pyelonephritis. Acute pyelonephritis was diagnosed if the patient had a fever of > 37.8 degrees C, loin pain or tenderness and infected urine (99% Escherichia coli). Patients had a blood culture taken (8 positive), as well as a hematological (leukocytosis 75%) and biochemical screen, C-reactive protein (CRP) (increased in 57 of 66 [86%]) and urinary tract ultrasonography. If the initial DMSA scan was abnormal it was repeated after three months and in some instances again at six months. If persisting defects were noted an intravenous urogram was then undertaken. Of the 81 patients, 37 (46%) had an abnormality on the DMSA scan. Nineteen had a single defect, 12 multifocal defects, five features suggestive of pre-existing renal parenchymal scarring (all later shown to have reflux nephropathy) and one a shrunken kidney. Those patients with an abnormal scan had a higher CRP concentration than those with a normal scan. Of the 31 patients who had either a focal or multifocal defect on their initial DMSA scan there was adequate follow-up on 24 patients. In 18 of these the defects had resolved by six months (usually within three months), while of the remainder, three were shown to have reflux nephropathy, one had a large single renal cyst and another an area of parenchymal calcification. Fifty-three of 76 patients (70%) had normal ultrasonography. In adults with acute pyelonephritis, the DMSA scan may prove to be the most useful renal imaging procedure.

The Nelson Prescribing Project. A programmed intervention in general practice in New Zealand.

We have defined the effect and acceptability of a locally developed general practice programme for the modification of prescribing. This voluntary programme consisted of prescription analysis and feedback, followed by visits from a pharmacist, a therapeutic bulletin on benzodiazepine prescribing, and use of a locally compiled preferred medicines list. A 3-month prescription sample from 26 general practitioners (GPs) fulfilling a stable practice definition was used to compare prescribing pre-project and mid-project. For 20 out of 26 GPs, prescribing of medicines on the preferred medicines list had increased significantly 8 months after the intervention programme had been introduced. Total prescription numbers and total medicines expenditure decreased by 8.3 and 4.9%, respectively, from 1988 to 1989. The decrease in benzodiazepine prescribing was marked (mean -22.2%, range -50.3 to +4%). The cooperative multimodel approach was highly successful in modifying prescribing in general practice.

Metabolic markers of hyperinsulinaemia in normotensive Maori and Caucasian New Zealanders.

New Zealand Maori are hyperinsulinaemic and insulin resistant, compared with age- and blood pressure-matched Caucasians and are therefore an important group in which to study previously described metabolic correlates of insulin resistance, including plasma urate, triglycerides and erythrocytic sodium. Only fasting triglycerides were associated with hyperinsulinaemia. Erythrocyte sodium and plasma urate were not correlated with fasting or stimulated insulin in either race. The reduced fractional urate clearance in Maori, compared with Caucasians, was positively correlated with fractional lithium clearance (proximal tubular sodium reabsorption), suggesting an ethnically expressed dependence of urate clearance on proximal tubular sodium reabsorption. Our findings indicate the need for caution in the generalisability of the variously described "markers" of hyperinsulinaemia.

Increase in haematocrit in borderline hypertensive men.

1. Haematologic parameters were measured in untreated borderline hypertensive (BHT) men, and weight and age matched with normotensive men to determine whether previously described increased haematocrit (Hct) in established hypertension is evident in borderline hypertension. 2. Haematocrit was significantly increased in BHT men (mean 0.46, s.d. 0.032) compared with normotensive men (mean 0.43, s.d. 0.014) and correlated significantly with mean arterial pressure in this group (r = 0.67, P = 0.036) independent of weight. 3. The correlation of blood pressure with Hct in BHT men supports the concept that increased Hct may contribute to increased blood viscosity and thus to raised arterial pressure.

Management of raised blood pressure in New Zealand: a discussion document.

A report to the National Advisory Committee on Core Health and Disability Support Services, New Zealand, on the management of raised blood pressure recommends that decisions to treat raised blood pressure should be based primarily on the estimated absolute risk of cardiovascular disease rather than on blood pressure alone. In general, patients with a blood pressure of 150-170 mm Hg systolic or 90-100 mm Hg diastolic, or both, should be given treatment to lower blood pressure if the risk of a major cardiovascular disease event in 10 years is more than about 20%. The results of clinical trials indicate that, at this level of absolute risk, 150 people would require treatment to reduce the annual number of cardiovascular events by about one. Implementation of these recommendations may result in a smaller proportion of people aged under 60, particularly women, receiving treatment but an increased proportion of older people treated. In the absence of specific contraindications, low dose diuretics and low dose beta blockers should be considered for first line treatment, since for only these drug groups is there direct evidence of reduced risk of stroke and coronary disease in people with raised blood pressure.

Transmembrane in vitro and in vivo sodium-lithium countertransport in New Zealand Maori.

1. Erythrocytic sodium-lithium (Na-Li) countertransport (CT) was measured in normotensive Maori and non-Maori by in vitro and in vivo methods to determine its relationship to erythrocytic hypernatraemia previously identified in Maori. 2. In vivo and in vitro CT rates were correlated within race and were similar between races. Countertransport rate was correlated with erythrocytic sodium concentration only in Maori. 3. The findings suggest the possibility of a genetically determined alteration in CT stoichiometry in Maori.