Biomedical subjects

Peter Herbison

Publications and source records attributed to Peter Herbison.

At least 37 records · Page 2Linked to original sources

PubMed2005

Statistical analysis of efficacy in falls prevention trials.

BACKGROUND: Many different and sometimes inappropriate statistical techniques have been used to analyze the results of randomized controlled trials of falls prevention programs for elderly people. This makes comparison of the efficacy of particular interventions difficult. METHODS: We used raw data from two randomized controlled trials of a home exercise program to compare the number of falls in the exercise and control groups during the trials. We developed two different survival analysis models (Andersen-Gill and marginal Cox regression) and a negative binomial regression model for each trial. These techniques a) allow for the fact that falls are frequent, recurrent events with a non-normal distribution; b) adjust for the follow-up time of individual participants; and c) allow the addition of covariates. RESULTS: In one trial, the three different statistical techniques gave surprisingly similar results for the efficacy of the intervention but, in a second trial, underlying assumptions were violated for the two Cox regression models. Negative binomial regression models were easier to use. CONCLUSION: We recommend negative binomial regression models for evaluating the efficacy of falls prevention programs.

Accidental Falls↗

PubMed2005

A novel instrument for assessing the retinal red reflex for non-ophthalmic health professionals.

BACKGROUND: The direct ophthalmoscope is the standard instrument for assessing retinal red reflexes when screening for cataract, however, it is expensive and often not available to non-ophthalmic health professionals. The pen torch ophthalmoscope is a new economic alternative for this purpose. This study aimed to determine its accuracy in assessing retinal red reflexes and to compare it to the direct ophthalmoscope. It is anticipated that this instrument will be useful in detecting both congenital and adult type cataracts. METHODS: Eighteen health professionals evaluated the retinal red reflexes of 68 subjects at the Dunedin Hospital Eye Clinic with both the direct ophthalmoscope and the pen torch ophthalmoscope. Three groups of seven, six and five observers assessed both eyes of 24, 21 and 23 subjects, respectively, resulting in 1,574 examinations. RESULTS: Compared to the direct ophthalmoscope, the pen torch ophthalmoscope exhibited lower sensitivity (68 per cent versus 75 per cent), but higher specificity (72 per cent versus 63 per cent) and lower over-referral (false positive) rates by nine per cent. The positive predictive value in respect to identifying for cataract was better for the pen torch ophthalmoscope (71 per cent) than for the direct ophthalmoscope (66 per cent), while the negative predictive value was slightly worse (70 per cent and 73 per cent, respectively). When compared to the direct ophthalmoscope, 15/18 observers felt the pen torch ophthalmoscope was accurate enough, one felt it was just as good and two did not respond. CONCLUSIONS: This pilot study demonstrates that the pen torch ophthalmoscope is comparable to the direct ophthalmoscope in detecting abnormal retinal red reflexes in adults with cataracts. At six per cent of the cost of a direct ophthalmoscope, it may appeal to non-ophthalmic health professionals in developed and developing countries. It may also increase the frequency of screening for cataract in children and adults. Further development and study of this pen torch ophthalmoscope prototype is warranted.

Cataract↗

PubMed2005

A cluster of thyrotoxicosis associated with consumption of a soy milk product.

OBJECTIVE: To determine whether a New Zealand cluster of thyrotoxicosis with low uptake on scintiscan was associated with soy milk consumption. METHOD: A case-control study was conducted, with controls matched by age, sex, and region. RESULTS: All cases (5/5) and one control (1/30) consumed soy milk before the index date. The cases all drank a brand of soy milk that had unexpectedly high levels of iodine. In a simple unmatched unadjusted analysis, the lower bound of the 95% confidence interval for the odds ratio was 19. CONCLUSION: This cluster was associated with consumption of a soy milk product. The thyrotoxicosis was probably due to iodine-induced thyrotoxicosis. IMPLICATIONS: This investigation raises issues about quality control in manufacturing processes and the monitoring of food products for their safety. It also raises issues about public and health professional awareness of the potential health effects from food additives in some processed foods.

Case-Control Studies↗

PubMed2005

Faecal incontinence and mode of first and subsequent delivery: a six-year longitudinal study.

OBJECTIVE: To investigate the prevalence of persistent and long term postpartum faecal incontinence and associations with mode of first and subsequent deliveries. DESIGN: Longitudinal study. SETTING: Maternity units in Aberdeen, Birmingham and Dunedin. POPULATION: Four thousand two hundred and fourteen women who returned postal questionnaires three months and six years postpartum. METHODS: Symptom data were obtained from both questionnaires and obstetric data from case-notes for the index birth and the second questionnaire for subsequent births. Logistic regression investigated the independent effects of mode of first delivery and delivery history. MAIN OUTCOME MEASURES: Incontinence to bowel motions three months and six years after index birth. For delivery history, the outcome was incontinence only at six years. RESULTS: The prevalence of persistent faecal incontinence was 3.6%. Almost 90% of these women reported no symptoms before their first birth. The forceps delivery of a first baby was independently predictive of persistent symptoms (OR 2.06, 95% CI 1.40-3.04). A caesarean section first birth was not significantly associated with persistent symptoms (OR 1.07, 95% CI 0.64-1.81). Delivering exclusively by caesarean section also showed no association with subsequent symptoms (OR 1.04, 95% CI 0.72-1.50) but ever having forceps was significantly predictive (OR 1.48, 95% CI 1.18-1.87). Other factors independently associated with persistent faecal incontinence were older maternal age, increasing number of births and Asian ethnic group. Birthweight and long second stage were not significantly associated. CONCLUSIONS: The risk of persistent faecal incontinence is significantly higher after a first delivery by forceps. We found no evidence of a lower risk of subsequent faecal incontinence for exclusive caesarean section deliveries.

Adult↗

PubMed2005

Incidence of thrombotic cardiovascular events in patients taking celecoxib compared with those taking rofecoxib: interim results from the New Zealand Intensive Medicines Monitoring Programme.

BACKGROUND: Rofecoxib was withdrawn from the market worldwide because of concerns relating to cardiovascular safety. There is conflicting evidence as to whether celecoxib, the most popular alternative to rofecoxib, carries the same cardiovascular risks. This study's aim was to compare the incidence of thrombotic cardiovascular events in patients taking celecoxib with patients taking rofecoxib. METHODS: Prescription event monitoring methodology was used in this prospective, longitudinal, observational cohort study, in which cohorts of patients were established from prescription data and thrombotic cardiovascular events were identified from follow-up questionnaires to patients' doctors and other sources. SUBJECTS: New Zealand patients with at least one prescription for either rofecoxib or celecoxib between 1 December 2000 and 30 November 2001. ANALYSIS: For this interim analysis the total cohorts were separated into three groups at different stages of follow-up: complete, incomplete and no follow-up. Cox's proportional hazards models were applied to calculate hazard ratios for celecoxib compared with rofecoxib. RESULTS: The total cohorts included 26,403 patients receiving rofecoxib and 32,446 patients receiving celecoxib. 4882 (18%) rofecoxib and 6267 (19%) celecoxib patients had been completely followed up. In this group the unadjusted hazard ratio for celecoxib compared with rofecoxib was 1.07 (95% CI 0.59, 1.93). After adjustment for age this hazard ratio was 0.94 (95% CI 0.51, 1.70). Further adjustment for sex, 'as required' use, indication for use, concomitant NSAID use and pre-existing cardiovascular disease resulted in only minor changes to the hazard ratio. CONCLUSION: This interim analysis of the Intensive Medicines Monitoring Programme data suggests that in 'real-life' postmarketing use in New Zealand there is no significant difference in the risk of cardiovascular thrombotic events in patients taking celecoxib compared with those taking rofecoxib.

Aged↗

PubMed2005

The incidence and expression of the subcondylar tubercle of the mandible in early Polynesians, modern Indians and modern Europeans.

A sample of pre-European Polynesian and Melanesian mandibles, modern Asian Indians and cadaveric European mandibles were investigated to establish the prevalence of a subcondylar tubercle and to attempt to relate its presence to mandibular function. Among the three population samples, the subcondylar tubercle appeared 1.5 times more frequently among the Polynesians/Melanesians, than either the Indian or European groups. It was fairly equally present on both sides in all three groups. Where it was present unilaterally, it was far more likely to be present on the left side. This left-side presence coincided with a significantly greater right-side condylar height and ramal width.

Adult↗

PubMed2004

Low back pain in young New Zealanders.

AIMS: To describe the occupational implications and impact of low back pain (LBP) in a birth cohort now aged 26. METHODS: The LBP data were collected by an interviewer-administered questionnaire. Study members were asked about the prevalence and frequency of LBP and, for the worst episode, details were sought on occupation, time off work or job limitation, the severity of the discomfort, and disability. RESULTS: The cohort comprised 980 individuals, and 969 individuals answered the questionnaire. Of these 969 individuals, 524 (54%) experienced LBP in the previous 12 months, with a modal frequency of three or more times a year. For the 448 individuals with a current occupation, there was no difference in the distribution of LBP between those with professional, clerical, and technical jobs and those with production or trades jobs. Fifty-six individuals had to have time off work (the majority for less than 7 days), and 13 individuals could not look after themselves because of pain. Based on data gathered on 26 year olds, the cost to the economy is estimated as NZ500 million dollars per annum. CONCLUSION: LBP is prevalent and disabling even in young people, and has high costs. The natural history of the disorder is still largely unknown, but work does play a part. Although getting a person back to work may still be the best treatment, it is important to address the workplace factors.

Absenteeism↗

PubMed2004

Full publication of abstracts of randomised controlled trials published at International Continence Society meetings'.

AIMS: To find out how many abstracts reporting randomised controlled trials (RCTs) that are submitted to scientific meetings of the International Continence Society (ICS) are later published in full, and any predictors of full publication. MATERIALS AND METHODS: The appropriate issues of "Neurourology and Urodynamics" and the Proceedings of the ICS for 1998 and 1999 were hand-searched for the abstracts reporting RCTs. Bibliographic databases (Cochrane Controlled Trials Register, MEDLINE, EMBASE, Healthstar, Psychlit, CINAHL) were searched, using the authors' names, to find full publications. Authors were contacted when no full publication was found to check that all full publications had been found. This was repeated for 1987. RESULTS: Sixty-three abstracts reporting RCTs were found in 1998 and 1999. Twenty-five of these (40%) were followed by full publication. The only characteristic that predicted full publication was the use of a no treatment control group. In 1987, 16 of 19 abstracts (84%) went on to be published in full. CONCLUSIONS: The rate of full publication of abstracts reporting RCTs submitted to recent ICS meetings is low. It is lower than the rate of 56% found in other meetings. As it is widely regarded as unethical not to publish in full, ICS members should make every effort to write-up studies for peer-reviewed publication.

Abstracting and Indexing↗

PubMed2004

Life expectancy of patients with neovascular glaucoma drained by Molteno implants.

PURPOSE: To determine the survival of patients with sighted eyes who had Molteno implants inserted for neovascular glaucoma. METHODS: Patients who had Molteno implants inserted for neovascular glaucoma between October 1977 and March 2001 at Dunedin Hospital, New Zealand, were reviewed. Relative survival analysis was then used to compare survival in this group to survival of the New Zealand population of the same age. RESULTS: A total of 114 patients had 131 Molteno implants inserted for neovascular glaucoma. Neovascular glaucoma was secondary to central retinal vein occlusion in 66 eyes (50%) and diabetes in 42 eyes (32%), and patients lost 52% or 6.53 years of their expected remaining life span. Age, sex and postoperative intraocular pressure control did not predict survival. The only predictor of improved survival was a preoperative visual acuity of 6/48 or better. These patients lost 21% (or 2.43 years) of expected remaining life compared to 62% (or 10.78 years) in those patients who had a presenting visual acuity of 6/60 or worse. CONCLUSIONS: Patients with neovascular glaucoma had a markedly reduced life expectancy, which has improved in recent years when compared to that of the normal sex and age-matched New Zealand population. Patients presenting with better vision (6/48 or better) survived significantly longer than those presenting with poorer vision.

Adult↗

PubMed2004

Voiding function after tension-free vaginal tape: a longitudinal study.

BACKGROUND: The tension-free vaginal tape (TVT) has become popular for the surgical treatment of urodynamic stress incontinence. It seems to function via an intermittent obstructive effect that is easily demonstrated on imaging, although there is no agreement regarding its effect on voiding. AIMS: The present study was designed to longitudinally evaluate flowmetry indices and voiding symptoms after TVT placement. METHODS: A total of 145 consecutive patients were seen at yearly intervals after TVT placement, and 108 have now attended at least twice. A standardised questionnaire was filled in and a clinical stress test performed. The patients were asked to void for flowmetry; ultrasound was performed translabially for residual urine, tape position and mobility. RESULTS: After TVT placement, maximum flow rate (MFR) centiles dropped from 49.66 (SD 32.45) to 22.86 (SD 23.56), P < 0.001. However, when first and last postoperative visits were compared, there was a significant increase in MFR centiles (20.07 (SD 20.83) to 24.92 (SD 23.94), P = 0.021). This effect appeared to be almost linear over time when analysed on anova. The residuals decreased highly significantly (P < 0.001). This was accompanied by a reduction in symptoms of voiding dysfunction such as 'poor stream' (P = 0.024), 'straining to void' (P = 0.038) and 'incomplete emptying' (P = 0.019). CONCLUSIONS: The tension-free vaginal tape reduces MFR and flow rate centiles. It can have an obstructive effect on voiding, although this does not appear to be a major clinical problem. Voiding seems to improve over time, and this is accompanied by a reduction in the prevalence of symptoms of voiding dysfunction.

Female↗

PubMed2004

Moment to force ratio characteristics of three Japanese NiTi and TMA dosing loops.

OBJECTIVES: This in vitro study investigated the loads ("forces"), moments and moment:force ratios (M:F) generated during activation and deactivation of three closing loop designs constructed from two different orthodontic wire alloys. METHOD: The forces and moments of non-preactivated vertical U-Loops, symmetrical T-Loops, and asymmetrical T-Loops (X-Loops) made from titanium molybdenum alloy (TMA) and Japanese nickel titanium alloy (NiTi) were measured at 35.6 degrees C +/- 0.5 degrees C. The M:F ratios generated during activation and deactivation were calculated for each loop. Analysis of covariance was used to identify statistical differences between loop material and design. RESULTS: The forces, moments and M:F ratios produced by the NiTi closing loops were significantly less than those from the TMA loops. NiTi T-Loops produced a relatively constant force during activation compared to the same design in TMA. The TMA X-loop produced a maximum M:F ratio of 9.4:1. No closing loop produced the optimum M:F ratio required for translational en masse tooth movement. CONCLUSIONS: Optimum M:F ratios for translation are not possible with non-preactivated vertical U-Loops, symmetrical T-Loops, and asymmetrical T-Loops (X-Loops) made of NiTi and TMA alloys.

Dental Alloys↗

PubMed2003

Utilization of preoperative urodynamic investigations by gynecologists who frequently operate for female urinary incontinence.

Our objective was to determine the availability and utilization of urodynamic investigations by gynecologists in the preoperative evaluation of women with urinary incontinence. Gynecologists in the UK, USA, Australia, New Zealand and Canada were asked what urodynamic investigations were required for four clinical scenarios. Analysis was restricted to frequent operators. Urodynamic investigations were available to 70% of frequent operators. For uncomplicated stress incontinence, cystometry was utilized by 72% of subspecialists and 44% of generalists ( P<0.001) who had access to urodynamic investigations. For stress incontinence and straining to void, uroflowmetry was utilized by 73% of subspecialists and 46% of generalists ( P<0.001) who had access to urodynamic investigations. We concluded that many gynecologists who frequently operate for female urinary incontinence do not have access to urodynamic investigations or do not utilize urodynamic investigations, or utilize investigations in a way that may be inadequate for the clinical problem. There are differences in utilization between subspecialists and generalists that are not explained by access. These observations could be explained by poor understanding or a lack of belief in the value of urodynamic investigations.

Aged↗

PubMed2003

Effectiveness of anticholinergic drugs compared with placebo in the treatment of overactive bladder: systematic review.

OBJECTIVE: To determine the effectiveness of anticholinergic drugs for the treatment of overactive bladder syndrome. DESIGN: Systematic review of randomised controlled trials. DATA SOURCES: Published papers and abstracts. STUDY SELECTION: Randomised controlled trials with anticholinergic drug treatment in one arm and placebo in another. DATA EXTRACTION: Primary outcomes of interest were patient perceived cure or improvement in symptoms, differences in number of incontinent episodes and number of voids in 24 hours, and side effects. Secondary outcomes of interest were urodynamic measures of bladder function (volume at first contraction, maximum cystometric capacity, and residual volume) and adverse events. DATA SYNTHESIS: 32 trials were included, totalling 6800 participants. Most trials were described as double blind but were variable in other aspects of quality. At the end of treatment, cure or improvement (relative risk 1.41, 95% confidence interval 1.29 to 1.54), differences in incontinent episodes in 24 hours (estimated mean difference 0.6, 0.4 to 0.8), number of voids in 24 hours (0.6, 0.4 to 0.8), maximum cystometric capacity (54 ml, 43 ml to 66 ml), and volume at first contraction (52 ml, 37 ml to 67 ml), were significantly in favour of anticholinergics (P<0.0001 for all). Anticholinergics were associated with significantly higher residual volumes (4 ml, 1 ml to 7 ml; P=0.02) and an increased rate of dry mouth (relative risk 2.56, 2.24 to 2.92; P<0.0001). Sensitivity analysis, although affected by small numbers of studies, showed little likelihood of an effect of age, sex, diagnosis, or choice of drug. CONCLUSIONS: Although statistically significant, the differences between anticholinergic drugs and placebo were small, apart from the increased rate of dry mouth in patients receiving active treatment. For many of the outcomes studied, the observed difference between anticholinergics and placebo may be of questionable clinical significance. None of these studies provided data on long term outcome.

Cholinergic Antagonists↗

PubMed2003

Same-sex attraction in a birth cohort: prevalence and persistence in early adulthood.

There is a continuing debate about the importance of social versus biological factors in the expression of same-sex attraction. Investigation of prevalence, continuities, and changes over time among young adults growing up in a country with a relatively accepting climate to homosexuality is likely to illuminate this debate. Analyses were therefore undertaken of self-reported same-sex attraction at age 21 and 26, in a cohort of about 1000 people born in 1972/3 in one New Zealand city. Participants were also asked about same-sex behaviour and attitudes to same-sex relationships. By age 26, 10.7% of men and 24.5% of women reported being attracted to their own sex at some time. This dropped to 5.6% of men and 16.4% of women who reported some current same-sex attraction. Current attraction predominantly to their own sex or equally to both sexes (major attraction) was reported by 1.6% of men and 2.1% of women. Occasional same-sex attraction, but not major attraction, was more common among the most educated. Between age 21 and 26, slightly more men moved away from an exclusive heterosexual attraction (1.9% of all men) than moved towards it (1.0%), while for women, many more moved away (9.5%) than towards (1.3%) exclusive heterosexual attraction. These findings show that much same-sex attraction is not exclusive and is unstable in early adulthood, especially among women. The proportion of women reporting some same-sex attraction in New Zealand is high compared both to men, and to women in the UK and US. These observations, along with the variation with education, are consistent with a large role for the social environment in the acknowledgement of same-sex attraction. The smaller group with major same-sex attraction, which changed less over time, and did not differ by education, is consistent with a basic biological dimension to sexual attraction. Overall these findings argue against any single explanation for homosexual attraction.

Adult↗

PubMed2003

Clinical utility of an electronic poisons information and clinical decision support tool.

The objective of the study was to assess the use of a computer toxicology database/clinical decision aid by clinical practitioners. The study investigated the sources that Emergency Department (ED) personnel use to obtain toxicology information and performed a quality audit of the current database. A questionnaire survey of ED staff was used in departments with access to the New Zealand Poisons Centre Substance Database (NZSD), a toxicology CD ROM computer database. Outcome measures were reported use of alternative data sources when managing clinical toxicology presentations and the qualities of the NZSD. Computer databases are commonly used for the management of clinical toxicology cases and the toxicology computer database/clinical decision aid studied is well accepted and used in Emergency Medicine practice. The users of the NZSD assessed the usability and quality of the information of the database.

Databases, Factual↗

PubMed2003

Prioritizing patients for elective surgery: a prospective study of clinical priority assessment criteria in New Zealand.

OBJECTIVES: Many hospitals in New Zealand have been using clinical priority assessment criteria (CPAC) to select and prioritize patients for access to publicly funded elective surgery. CPAC usually consist of clinical, patient-experienced, and social measures. The objective of this study was to determine how robust patient rankings were and the extent to which the patients selected were those who benefited the most from surgery. METHODS: Patients prioritized for cataract (n = 101), prostate (n = 103), and hip or knee joint replacement (n = 137) surgery according to CPAC were assessed using the EQ-5D, SF-12, and condition-related patient-experienced health status measures before and after treatment. Correlations between the rankings of patients on the CPACs and the alternative instruments were explored. RESULTS: For each surgery group, the CPAC ranking of patients was not strongly correlated with rankings obtained using their before-treatment EQ-5D (valued) profiles or the SF-12, although there was some correlation with rankings according to the condition-related measures. Improvements in the health status of patients who were operated on, as measured by the change in their EQ-5D values, were poorly correlated with equivalent changes on the SF-12 and condition-related measures. Patients' baseline health status according to the CPAC, the EQ-5D, and the SF-12 patient-experienced measures was only slightly related to the magnitude of benefit following surgery. The strongest predictors of improvement in health status were the baseline condition-related measures. CONCLUSIONS: The current method of prioritizing patients in New Zealand requires reconsideration, although a gold standard method for prioritization is not immediately apparent from these results.

Arthroplasty, Replacement↗

PubMed2003

Dental and occlusal changes during mandibular advancement splint therapy in sleep disordered patients.

The aims of this longitudinal, observational study were two-fold: first, to determine in adults with sleep disorders the extent of dental and occlusal changes following the use of a mandibular advancement splint (MAS) and, second, to determine the time course of these changes. One hundred adult subjects (87 males, 13 females) diagnosed with obstructive sleep apnoea (OSA) and/or asymptomatic snoring were treated with non-adjustable MAS. At the outset each subject was randomly assigned to a group and reviewed 6, 12, 18, 24 or 30 months after placement of a splint. There were 20 subjects in each group. Craniofacial changes were measured on lateral cephalometric radiographs taken at the initial and review appointments. When the changes in all subjects were examined, the SNA, ANB angles, ANS-PNS length and face height increased, and the mandibular first molars and the maxillary first premolars significantly overerupted. Significant retroclination of the maxillary incisors and proclination of the mandibular incisors were accompanied by reductions in maxillary arch length, overbite and overjet. When the changes over time were determined, the mandibular symphysis was significantly lower at all review periods. An increase in face height and reductions in overbite and overjet were evident at 6 months, and over-eruption of the maxillary first premolars and mandibular first molars, and proclination of the lower incisors were found at 24 months. Significant positive correlations were also found between the amount of anterior opening by the appliances and changes in overbite at 24 and 30 months. The appliance used produced small, unpredictable changes in the occlusion that tended to occur after 24 months' wear. It is postulated that the changes in overbite might be lessened by keeping the bite opening to a minimum.

Adult↗

PubMed2002

Unwanted pregnancies involving young women and men in a New Zealand birth cohort.

AIMS: To examine the circumstances of wanted and unwanted pregnancies before age 25 years for both women and men, and compare the circumstances of the most undesired pregnancies with all others. METHODS: Cross-sectional study within a birth cohort using a computer-presented questionnaire. RESULTS: Of the 477 women, 173 (36%) had been pregnant before age 25 years, and experienced 289 pregnancies of which 173 (60%) were unwanted. Of the 489 men, 142 (29%) reported 225 pregnancies before age 25, of which 165 (73%) were unwanted. By age 25 about a quarter of the study members (27% of women and 24% of men), had been involved in at least one unwanted pregnancy. Wantedness increased with age and length of relationship with the other parent; both factors remained significant in multivariate analysis for men, but not age for women. For women unwanted pregnancies were more likely to be due to non-use of contraception than failure. For both women and men the commonest single reason for not using contraception was not thinking about it, followed by alcohol use. CONCLUSIONS: An environment has emerged for men and women in their twenties in New Zealand where most are sexually active but do not want a pregnancy to occur. To delay pregnancy for a prolonged period requires dedication and commitment to effective contraception. While more attention needs to be paid to promotion of effective use of contraception, more understanding is called for over the difficulties of avoiding pregnancy with long-term reversible contraception. A further approach to the problem of unwanted pregnancies which should be investigated is to encourage committed sexual relationships.

Adolescent↗