A meta-epidemiological study of bias in randomized clinical trials of open and laparoscopic surgery.

BACKGROUND: Blinding, random sequence generation, and allocation concealment are established strategies to minimize bias in RCTs. Meta-epidemiological studies of drug trials have demonstrated exaggerated treatment effects in RCTs where such methods were not employed. As blinding is more difficult in surgical trials it is important to determine whether this applies to them. The study aimed to investigate this using systematic meta-epidemiological methods. METHOD: The Cochrane Database of Systematic Reviews was searched for systematic reviews of RCTs that compared laparoscopic and open abdominal surgical procedures. Each review was then scrutinized to determine whether at least one of the included trials was blinded. Eligible reviews were updated and individual RCTs retrieved. Extracted data included the primary outcomes of interest (length of stay and complications), secondary outcomes and a risk of bias assessment. A multistep meta-regression analysis was then performed to obtain an overall difference in the reported outcome differences between trials that employed each bias-minimization strategy, and those that did not. RESULTS: Some 316 RCTs were included, reporting on eight different procedures. Patient-blinded RCTs reported a smaller difference in length of stay between laparoscopic and open groups (difference of standardized mean differences -0·36 (95 per cent c.i. -0·73 to 0·00)) and complications (ratio of odds ratios 0·76 (95 per cent c.i. 0·61 to 0·93)). Blinding of postoperative carers and outcome assessors had similar effects. CONCLUSION: Lack of blinding significantly altered the treatment effect estimates of RCTs comparing laparoscopic and open surgery. Blinding should be implemented in surgical RCTs where possible to avoid systematic bias.

Network meta-analysis of surgical management of gastro-oesophageal reflux disease in adults.

BACKGROUND: Proton pump inhibitors are the mainstay of treatment for gastro-oesophageal reflux disease, but are associated with ongoing costs and side-effects. Antireflux surgery is cost-effective and is preferred by many patients. A total (360o or Nissen) fundoplication is the traditional procedure, but other variations including partial fundoplications are also commonly performed, with the aim of achieving durable reflux control with minimal dysphagia. Many RCTs and some pairwise meta-analyses have compared some of these procedures but there is still uncertainty about which, if any, is superior. Network meta-analysis allows multiple simultaneous comparisons and robust synthesis of the available evidence in these situations. A network meta-analysis comparing all antireflux procedures was performed to identify which has the most favourable outcomes at short-term (3-12 months), medium-term (1-5 years) and long-term (10 years and more than 10 years) follow-up. METHODS: Article databases were searched systematically for all eligible RCTs. Primary outcomes were quality-of-life measures and dysphagia. Secondary outcomes included reflux symptoms, pH studies and complications. RESULTS: Fifty-one RCTs were included, involving 5357 patients and 14 different treatments. Posterior partial fundoplication ranked best in terms of reflux symptoms, and caused less dysphagia than most other interventions including Nissen fundoplication. This was consistent across all time points and outcome measures. CONCLUSION: Posterior partial fundoplication provides the best balance of long-term, durable reflux control with less dysphagia, compared with other treatments.

Network meta-analysis of the effect of preoperative carbohydrate loading on recovery after elective surgery.

BACKGROUND: Three meta-analyses have summarized the effects of preoperative carbohydrate administration on postoperative outcomes in adult patients undergoing elective surgery. However, these studies could not account for the different doses of carbohydrate administered and the different controls used. Multiple-treatments meta-analysis allows robust synthesis of all available evidence in these situations. METHODS: Article databases were searched systematically for RCTs comparing preoperative carbohydrate administration with water, a placebo drink, or fasting. A four-treatment multiple-treatments meta-analysis was performed comparing two carbohydrate dose groups (low, 10-44 g; high, 45 g or more) with two control groups (fasting; water or placebo). Primary outcomes were length of hospital stay and postoperative complication rate. Secondary outcomes included postoperative insulin resistance, vomiting and fatigue. RESULTS: Some 43 trials involving 3110 participants were included. Compared with fasting, preoperative low-dose and high-dose carbohydrate administration decreased postoperative length of stay by 0·4 (95 per cent c.i. 0·03 to 0·7) and 0·2 (0·04 to 0·4) days respectively. There was no significant decrease in length of stay compared with water or placebo. There was no statistically significant difference in the postoperative complication rate, or in most of the secondary outcomes, between carbohydrate and control groups. CONCLUSION: Carbohydrate loading before elective surgery conferred a small reduction in length of postoperative hospital stay compared with fasting, and no benefit in comparison with water or placebo.

Musculoskeletal disorders among nurses compared with two other occupational groups.

BACKGROUND: There is a high incidence of low back pain (LBP) among nurses. However, few longitudinal studies have investigated musculoskeletal disorders (MSDs) at other anatomical sites in nurses. AIMS: To describe the cumulative incidence and persistence/recurrence of MSDs of the low back, neck, shoulder, elbow, wrist/hand and knee among New Zealand nurses, to investigate the impact of MSDs on work and functional tasks and to compare findings for nurses with those in postal workers and office workers. METHODS: Participants completed a postal survey at baseline and again 1 year later. Information was collected about MSDs in the previous 1 month and 12 months and about the ability to attend work, undertake work duties and perform functional tasks. RESULTS: Among nurses, the low back was the site with the highest cumulative incidence and highest prevalence of persistent/recurrent, work-disabling and functional-task-disabling pain. Work-disabling LBP was more prevalent among nurses and postal workers than office workers (P < 0.001). Nurses had a substantial prevalence of work-disabling shoulder pain (10%) and functional-task-disabling knee (19%) and wrist/hand pain (16%). With the exception of the elbow, each occupational group had a high prevalence of persistent/recurrent MSDs at all anatomical sites. CONCLUSIONS: LBP continues to have a substantial impact among nurses. Other less commonly considered MSDs, such as shoulder, wrist/hand and knee pain, also made work or functional tasks difficult, suggesting that primary and secondary prevention efforts should consider MSDs at other anatomical sites as well as the low back.

Twelve-year follow-up of conservative management of postnatal urinary and faecal incontinence and prolapse outcomes: randomised controlled trial.

OBJECTIVE: To determine the long-term (12-year) effects of a conservative nurse-led intervention for postnatal urinary incontinence. DESIGN: Follow-up of a randomised controlled trial. SETTING: Community-based intervention in three centres (in the UK and New Zealand). POPULATION: A cohort of 747 women with urinary incontinence at 3 months after childbirth, of whom 471 (63%) were followed up after 12 years. METHODS: Women were randomly allocated to active conservative treatment after delivery (pelvic floor muscle training and bladder training), or to a control group receiving standard care. MAIN OUTCOME MEASURES: Prevalence of urinary incontinence (primary outcome) and faecal incontinence, symptoms and signs of prolapse, and performance of pelvic floor muscle training at 12 years. RESULTS: The significant improvements relative to controls that had been found in urinary incontinence (60 versus 69%; risk difference, RD, -9.1%; 95% confidence interval, 95% CI, -17.3 to -1.0%) and faecal incontinence (4 versus 11%; RD -6.1%; 95% CI -10.8 to -1.6%) at 1 year did not persist for urinary incontinence (83 versus 80%; RD 2.1%; 95% CI -4.9 to 9.1%) or faecal incontinence (19 versus 15%; RD 4.3%; 95% CI -2.5 to 11.0%) at the 12-year follow up, irrespective of incontinence severity at trial entry. The prevalence of prolapse symptoms or objectively measured pelvic organ prolapse also did not differ between the groups. In the short term the intervention motivated more women to perform pelvic floor muscle training (83 versus 55%), but this fell in both groups by 12 years (52 versus 49%). CONCLUSIONS: The moderate short-term benefits of a brief nurse-led conservative treatment for postnatal urinary incontinence did not persist. About four-fifths of women with urinary incontinence 3 months after childbirth still had this problem 12 years later.

Exhaled nitric oxide and pulmonary artery pressures during graded ascent to high altitude.

Nitric oxide (NO) is a potent vasodilator that regulates pulmonary vascular tone. During ascent to high altitude, pulmonary vascular tone increases leading to pulmonary hypertension. To explore the mechanisms underpinning this effect, we investigated the relationship between exhaled NO (P(E(NO)); nm Hg) and pulmonary artery systolic pressure (PASP; mm Hg) in 11 healthy adults during hypoxic challenge at sea level [with oxygen saturations (S(P(O(2)))) of 80% and 90%] and at intervals during graded ascent to 5050 m. During normobaric hypoxia, PASP progressively increased from 22.7 mm Hg to 33.5 mm Hg (p=0.006), whilst P(E(NO)) remained unchanged. In contrast, during ascent to high altitude, PASP increased progressively from 22.7 mm Hg to 39.1 mm Hg (p<0.001), but P(E(NO)) decreased from 18.8 nm Hg to 9.0 nm Hg (p<0.001). However, after appropriate adjustments, P(E(NO)) had no significant effect on PASP at altitude (p=0.309). These findings indicate that although exhaled NO decreases with altitude, it does not appear to be a major contributor to hypoxic pulmonary vasoconstriction.

Ascertainment of occupational histories in the working population: the occupational history calendar approach.

BACKGROUND: self-reported occupational histories are an important means for collecting historical data in epidemiological studies. An occupational history calendar (OHC) has been developed for use alongside a national occupational hazard surveillance tool. This study presents the systematic development of the OHC and compares work histories collected via this calendar to those collected via a traditional questionnaire. METHODS: the paper describes the systematic development of an OHC for use in the general working population. A comparison of data quality and recall was undertaken in 51 participants where both tools were administered. RESULTS: the OHC enhanced job recall compared with the traditional questionnaire. Good agreement in the data captured by both tools was observed, with the exception of hazard exposures. CONCLUSIONS: a calendar approach is suitable for collecting occupational histories from the general working population. Despite enhancing job recall the OHC approach has some shortcomings outweighing this advantage in large-scale population surveillance.

The impact of body mass index on semen parameters and reproductive hormones in human males: a systematic review with meta-analysis.

BACKGROUND: It has been suggested that body mass index (BMI), especially obesity, is associated with subfertility in men. Semen parameters are central to male fertility and reproductive hormones also play a role in spermatogenesis. This review aimed to investigate the association of BMI with semen parameters and reproductive hormones in men of reproductive age. METHODS: MEDLINE, EMBASE, Biological Abstracts, PsycINFO and CINAHL databases and references from relevant articles were searched in January and February 2009. Outcomes included for semen parameters were sperm concentration, total sperm count, semen volume, motility and morphology. Reproductive hormones included were testosterone, free testosterone, estradiol, FSH, LH, inhibin B and sex hormone binding globulin (SHBG). A meta-analysis was conducted to investigate sperm concentration and total sperm count. RESULTS: In total, 31 studies were included. Five studies were suitable for pooling and the meta-analysis found no evidence for a relationship between BMI and sperm concentration or total sperm count. Overall review of all studies similarly revealed little evidence for a relationship with semen parameters and increased BMI. There was strong evidence of a negative relationship for testosterone, SHBG and free testosterone with increased BMI. CONCLUSIONS: This systematic review with meta-analysis has not found evidence of an association between increased BMI and semen parameters. The main limitation of this review is that data from most studies could not be aggregated for meta-analysis. Population-based studies with larger sample sizes and longitudinal studies are required.

Long-term functional outcome and performance status after intensive care unit re-admission: a prospective survey.

BACKGROUND: Intensive care unit (ICU) re-admission identifies a high-risk group in terms of hospital mortality, length of stay, and resource utilization. Only hospital and ICU mortality are well described in the literature on critically ill patients needing re-admission. METHODS: With ethical committee approval, from a prospectively collected database of all admissions to a combined medical and surgical ICU from January 1 to December 31, 2004, we identified all ICU re-admissions from within the hospital and analysed the factors associated with increased incidence of re-admission. At 2-3 yr after discharge, we evaluated the functional outcome of the surviving re-admitted patients as Glasgow Outcome Score (GOS) and Karnofsky index and identified determinants of both mortality and good functional outcome. RESULTS: Seventy-three (7.4%) of the 1061 patients who survived their first ICU stay were re-admitted during the study period. Of the 73 re-admitted patients, 14 died in ICU, 17 died later in the same hospital stay, and 10 died in the interim. Thus, 32 (43.8%) were alive 2-3 yr after discharge. The median [IQR] GOS of the survivors was 4 (see Mackle and colleagues in One year outcome of intensive care patients with decompensated alcoholic liver disease. CONCLUSIONS: Although the ICU, hospital, and subsequent mortalities are high in patients after ICU re-admission, most survivors at 2-3 yr had by then made a good functional recovery and were independent.

Botulinum toxin injections for adults with overactive bladder syndrome.

BACKGROUND: Overactive bladder syndrome is a common condition with a significant negative impact on quality of life. Intravesical injection of botulinum toxin is increasingly used as an intervention for refractory overactive bladder, with a considerable body of case reports and series in the literature suggesting beneficial effects. OBJECTIVES: The objective was to compare intravesical botulinum toxin injection with other treatments for neurogenic and idiopathic overactive bladder in adults. The hypotheses addressed were whether intravesical injection of botulinum toxin was better: than placebo or no treatment, pharmacological and other non-pharmacological interventions, whether higher doses of botulinum toxin were better than lower doses, whether botulinum toxin in combination with other treatments was better than other treatments alone, whether one formulation of botulinum toxin is better than another, and whether one injection technique was better than another. SEARCH STRATEGY: We searched the Cochrane Incontinence Group Specialised Trials Register (searched 22 November 2005). The register contains trials identified from MEDLINE, CINAHL, the Cochrane Central Register of Controlled Trials (CENTRAL), and handsearching of journals and conference proceedings. Additionally, all reference lists of selected trials were searched. No limitations were placed on the searches. SELECTION CRITERIA: All randomised or quasi-randomised controlled trials of treatment for overactive bladder syndrome in adults in which at least one management arm involved intravesical injection of botulinum toxin were included. Participants had either neurogenic or idiopathic overactive bladder with or without stress incontinence. Comparison interventions could include no intervention; placebo; lifestyle modification; bladder retraining; pharmacological treatments; surgery; bladder instillation techniques; neuromodulation; and different types, doses, and injection techniques of botulinum toxin. DATA COLLECTION AND ANALYSIS: Binary outcomes were presented as relative risk and continuous outcomes by mean differences. No data could be synthesised across studies due to differing designs and outcome measures. Data were tabulated where possible with results taken from trial reports where this was not possible. Where multiple publications were found, the reports were treated as a single source of data. MAIN RESULTS: Eight studies met the inclusion criteria. Results varied between studies. For the most part, studies reported superiority of botulinum toxin A to placebo in such outcomes as incontinence episodes, bladder capacity, maximum detrusor pressure, and quality of life. Low doses of botulinum toxin (100U to150U) appeared to have beneficial effects, but higher doses (300U) may have been more effective. Botulinum toxin appeared to have beneficial effects in overactive bladder that quantitatively exceeded the effects of intravesical resiniferatoxin. AUTHORS' CONCLUSIONS: Intravesical botulinum toxin shows promise as a therapy for overactive bladder symptoms, but as yet too little controlled trial data exist on benefits and safety compared with other interventions, or with placebo. Practitioners should be aware that at present there is little more than anecdotal evidence, in the form of case reports to support the efficacy of intravesical botulinum toxin; there is not much in the way of substantial, robust safety data. Furthermore, the optimal dose of botulinum toxin for efficacy and safety has not yet been demonstrated.

Laparoscopic colposuspension for urinary incontinence in women.

BACKGROUND: Laparoscopic colposuspension was one of the first minimal access operations for the treatment of women with stress urinary incontinence, with the presumed advantages over traditional Burch colposuspension of avoiding major incisions, shorter hospital stay, and quicker return to normal activities. A variety of approaches and methods are used. OBJECTIVES: To determine the effects of laparoscopic colposuspension for urinary incontinence. SEARCH STRATEGY: We searched the Cochrane Incontinence Group Specialised Trials Register (searched 21 September 2005). Additional trials were sought from other sources such as reference lists, reviews and researchers and authors were contacted for unpublished data and trials. SELECTION CRITERIA: Randomised or quasi-randomised controlled trials in women with symptomatic or urodynamic diagnosis of stress or mixed incontinence that included laparoscopic surgery in at least one arm of the study. DATA COLLECTION AND ANALYSIS: Trials were evaluated for methodological quality and appropriateness for inclusion by the reviewers. Data were extracted by two of the reviewers and cross checked by another. Trial data were analysed by intervention. Where appropriate, a summary statistic was calculated. MAIN RESULTS: Twenty-one eligible trials were identified. Nine involved the comparison of laparoscopic with open colposuspension. Whilst the women's subjective impression of cure seemed similar for both procedures in the short and medium term follow-up, there was some evidence of poorer results of laparoscopic colposuspension, within 18 months, on objective outcomes. Two poor quality trials reported conflicting long term results (after five years) for this comparison. No significant differences were observed for post-operative urgency, voiding dysfunction or de novo detrusor overactivity. Trends were shown towards a lower perioperative complication rate, longer operating time, less intraoperative blood loss, less postoperative pain, shorter hospital stay, quicker return to normal activities, and shorter duration of catheterisation for laparoscopic compared with open colposuspension. Benefits did not come without a price, as laparoscopic colposuspension in the short term is more costly.Eight studies compared laparoscopic colposuspension with newer 'self-fixing' vaginal slings. Overall there were no significant differences in the reported subjective cure rates of the two procedures, however vaginal sling procedures did have significantly higher objective cure rates at 18 months. No significant differences were observed for post-operative voiding dysfunction, de novo detrusor activity and perioperative complications. Laparoscopic colposuspension has a significantly longer operation time, longer hospital stay and slower return to normal activities when compared to the sling procedures. Significantly higher subjective and objective (dry on 'ultrashort' pad test) one year cure rates were found for women randomised to two paravaginal sutures compared with one suture in a single trial (89% versus 65% and 83% versus 58% respectively). Two small studies compared sutures with mesh and staples for laparoscopic colposuspension and the comparisons, although showing a trend towards favouring the sutures, were not significant. One study compared transperitoneal with extraperitoneal access for laparoscopic colposuspension but it was also small and of poor quality. AUTHORS' CONCLUSIONS: The long-term performance of laparoscopic colposuspension remains uncertain. Currently available evidence suggests that it may be as good as open colposuspension at two years post surgery. Like other laparoscopically performed operations, patients having laparoscopic colposuspension recovered quicker, but the operation itself took longer to perform. However, the newer vaginal sling procedures appear to offer even greater benefits of minimal access surgery and better objective outcomes in the short-term. If laparoscopic colposuspension is performed, two paravaginal sutures appear to be more effective than one. The place of laparoscopic colposuspension in clinical practice should become clearer when ongoing trials are reported and when there are more data available describing long-term cure results.

A randomised clinical trial to investigate bond failure rates using a self-etching primer.

This clinical trial evaluated, over a 12-month period, the performance of brackets bonded to teeth etched and primed with Transbond Plus Self-Etching Primer (SEP) when compared with a conventional separate two-step etch and primer system. Thirty-nine randomly selected patients requiring fixed appliance therapy were entered into the study. Random allocation of each etching system, along with a 'split-mouth cross-quadrant' design was used. A total of 661 brackets were placed by two operators. The failure and survival rates of the brackets were determined for age and gender of the patients, each etching system, operator, mode of failure, tooth position in the dental arch, and number of manipulations prior to curing the adhesive. Statistical analysis showed that SEP had a significantly higher bond failure rate (11.2 per cent) than the conventional etch and primer system (3.9 per cent) at the P = 0.001 level. Cox's proportional hazards regression showed the conventional etch and primer system to have a 60 per cent reduced chance of bracket failure over a 12-month observation period, while males had a 2.4 times increased risk compared with females. The predominant mode of failure was at the composite enamel interface for the SEP, while for the conventional etch and primer system, it was within the composite adhesive. No statistically significant differences were found for the failure rate with respect to the age of the patient, operator, tooth location, or the number of manipulations of the bracket. This in vivo study showed that brackets bonded using SEP had an increased clinical bond failure rate compared with the conventional, separate, etch and prime system.

New postnatal urinary incontinence: obstetric and other risk factors in primiparae.

OBJECTIVE: To identify obstetric and other risk factors for urinary incontinence that occurs during pregnancy or after childbirth. DESIGN: Questionnaire survey of women. SETTING: Maternity units in Aberdeen (Scotland), Birmingham (England) and Dunedin (New Zealand). POPULATION: A total of 3405 primiparous women with singleton births delivered during 1 year. METHODS: Questionnaire responses and obstetric case note data were analysed using multivariate analysis to identify associations with urinary incontinence. MAIN OUTCOME MEASURES: Urinary incontinence at 3 months after delivery first starting in pregnancy or after birth. RESULTS: The prevalence of urinary incontinence was 29%. New incontinence first beginning after delivery was associated with older maternal age (oldest versus youngest group, OR 2.02, 95% CI 1.35-3.02) and method of delivery (caesarean section versus spontaneous vaginal delivery, OR 0.28, 95% CI 0.19-0.41). There were no significant associations with forceps delivery (OR 1.18, 95% CI 0.92-1.51) or vacuum delivery (OR 1.16, 95% CI 0.83-1.63). Incontinence first occurring during pregnancy and still present at 3 months was associated with higher maternal body mass index (BMI>25, OR 1.68, 95% CI 1.16-2.43) and heavier babies (birthweight in top quartile, OR 1.56, 95% CI 1.12-2.19). In these women, caesarean section was associated with less incontinence (OR 0.39, 95% CI 0.27-0.58) but incontinence was not associated with age. CONCLUSIONS: Women have less urinary incontinence after a first delivery by caesarean section whether or not that first starts during pregnancy. Older maternal age was associated with new postnatal incontinence, and higher BMI and heavier babies with incontinence first starting during pregnancy. The effect of further deliveries may modify these findings.

Interventions for protecting renal function in the perioperative period.

BACKGROUND: A number of methods have been used to try to protect kidney function in patients undergoing surgery. These include the administration of dopamine, diuretics, calcium channel blockers, angiotensin converting enzyme inhibitors and hydration fluids. OBJECTIVES: For this review, we selected randomized controlled trials, which employed different methods to protect renal function during the perioperative period. In examining these trials, we looked at outcomes such as renal failure and mortality, as well as changes in the renal function tests, including urine output, creatinine clearance, free water clearance, fractional excretion of sodium and renal plasma flow. SEARCH STRATEGY: We searched the Cochrane Central register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 4, 2004), MEDLINE (1966 to 2004) and EMBASE (1988 to 2004) and hand searched six journals (British Journal of Anaesthesia; Anesthesia and Analgesia; Anesthesiology; Annals of Surgery; Journal of Thoracic and Cardiovascular Surgery and Journal of Vascular Surgery). SELECTION CRITERIA: We selected all randomized controlled trials in adult population undergoing surgery where a treatment measure was used for the purpose of renal protection in the perioperative period. DATA COLLECTION AND ANALYSIS: We selected 37 studies for inclusion in this review. As well as analysis of the data from all the studies, we also performed subgroup analysis for type of interventions, types of surgical procedures and those with pre-existing renal dysfunction. We undertook sensitivity analysis on studies with high methodological quality. MAIN RESULTS: The review included data from 37 studies, comprising a total of 1227 patients. Of these, 658 received some form of treatment and 569 acted as controls. The interventions were mostly employing different pharmaceutical agents such as dopamine, diuretics, calcium channel blockers. ACE inhibitors or selected hydration fluids. The results indicated that certain interventions showed some benefits, but all the results suffered from significant heterogeneity. Hence we can draw no conclusions about the effectiveness of these interventions in protecting the kidneys during surgery. AUTHORS' CONCLUSIONS: There is no reliable evidence from available literature to suggest that interventions during surgery can protect the kidneys from damage. However, there is a need for more studies of high methodological quality. One particular area for further studies may be on patients with pre-existing renal dysfunction undergoing surgery.

Assessing individual employee risk factors for occupational asthma in primary aluminium smelting.

AIMS: To assess the significance of individual risk factors in the development of occupational asthma of aluminium smelting (OAAS). METHODS: A matched case-control study nested in a cohort of 545 workers employed in areas with moderate to high levels of smelting dust and fume. The cohort comprised those who had their first pre-employment medical examination between 1 July 1982 and 1 July 1995; follow up was until 31 December 2000. Forty five cases diagnosed with OAAS and four controls per case were matched for the same year of pre-employment and age within +/-5 years. The pre-employment medical questionnaires were examined, blinded as to case-control status, and information obtained on demographics and details of allergic symptoms, respiratory risk factors, respiratory symptoms, and spirometry. Data from the subsequent medical notes yielded subsequent history of hay fever, family history of asthma, full work history, date of termination or diagnosis, and tobacco smoking history at the end-point. RESULTS: There was a significant positive association between hay fever diagnosed either at or during employment and OAAS (adjusted OR 3.58, 95% CI 1.57 to 8.21). A higher forced expiratory ratio (FEV1/FVC%) at employment reduced the risk of developing OAAS (adjusted OR 0.93, 95% CI 0.88 to 0.99). The risk of OAAS was more than three times higher in individuals with an FER of 70.0-74.9% than in individuals with an FER > or =80.0% (adjusted OR 3.46, 95% CI 1.01 to 11.89). CONCLUSIONS: Individuals with hay fever may be more susceptible to occupational asthma when exposed to airborne irritants in aluminium smelting. The pathological basis may be reduced nasal filtration and increased bronchial hyperresponsiveness.

Relationship between socioeconomic status and asthma: a longitudinal cohort study.

BACKGROUND: There is conflicting information about the relationship between asthma and socioeconomic status, with different studies reporting no, positive, or inverse associations. Most of these studies have been cross sectional in design and have relied on subjective markers of asthma such as symptoms of wheeze. Many have been unable to control adequately for potential confounding factors. METHODS: We report a prospective cohort study of approximately 1000 individuals born in Dunedin, New Zealand in 1972-3. This sample has been assessed regularly throughout childhood and into adulthood, with detailed information collected on asthma symptoms, lung function, airway responsiveness, and atopy. The prevalence of these in relation to measures of socioeconomic status were analysed with and without controls for potential confounding influences including parental history of asthma, smoking, breast feeding, and birth order using cross sectional time series models. RESULTS: No consistent association was found between childhood or adult socioeconomic status and asthma prevalence, lung function, or airway responsiveness at any age. Having asthma made no difference to educational attainment or socioeconomic status by age 26. There were trends to increased atopy in children from higher socioeconomic status families consistent with previous reports. CONCLUSIONS: Socioeconomic status in childhood had no significant impact on the prevalence of asthma in this New Zealand born cohort. Generalisation of these results to other societies should be done with caution, but our results suggest that the previously reported associations may be due to confounding.

Age of menarche: the role of some psychosocial factors.

BACKGROUND: The goal of this study was to determine associations between the age of first menstrual period (menarche) and adverse childhood experiences in a random community sample of New Zealand women. Previous reports have linked early menarche to absence of a live-in father figure and to family conflict, as well as genetic determination of early puberty and adiposity. METHOD: Two groups of women randomly selected from the community on their responses to a mailed screening questionnaire on childhood sexual abuse (CSA) were interviewed in detail. Data about their childhood experiences, including age of menarche, were collected on two occasions, 6 years apart. Early menarche was defined as first menstruation occurring before the age of 12 years. RESULTS: Univariate analyses identified a number of adverse childhood experiences preceded early menarche, which was reported by 20.3% of this sample. These included low family socio-economic status, absence of father, a number of variables showing family conflict, poor relationships between the girl and either/both parents, a self-rated childhood personality style as a loner, childhood physical and sexual abuse. Sequential modelling showed parental rows, being a loner and the duration of CSA to be most important, although lack of a father and any CSA were each also independently associated with early menarche. No variables survived the modelling exercise as predictors of early menarche for those women who did not report childhood sexual abuse. CONCLUSIONS: The identified variables statistically interacted with each other in a highly complex manner. The attempt to rank their importance was only partially successful, for methodological reasons (half the sample reporting CSA). Chronic or protracted CSA needs to be added to the list of factors associated with early menarche in future studies.

Bronchodilator tolerance: the impact of increasing bronchoconstriction.

Chronic exposure to beta-agonists causes tolerance to their bronchodilator effects, which is best demonstrated during acute bronchoconstriction. The aim of the present study was to assess whether tolerance becomes more evident with increasing bronchoconstriction, as might occur in acute asthma. In a randomised, double-blind, placebo-controlled, crossover study comprising 15 patients, the treatments were salbutamol 400 microg q.i.d. or placebo given via Diskhaler for 28 days with a 2-week washout between treatments. Patients attended on days 14, 21 and 28. Bronchoconstriction was induced on two of these three occasions to achieve a reduction in the forced expiratory volume in one second (FEV1) of 0 (no methacholine), 15 and 30% (using methacholine) in a randomised order. Immediately after this, salbutamol 100 microg, 100 microg and 200 microg was inhaled at 0, 5, and 10 min. FEV1 was measured over 40 min. Dose/response curves were plotted and values for the area under the curve (AUC)0-40 FEV1 were compared between treatments and by degree of bronchoconstriction. Regular salbutamol resulted in attenuation of the acute response to beta-agonist, which was increasingly evident with greater bronchoconstriction. With a reduction in FEV1 of 0, 15 and 30%, the AUC0-40 FEV1 with salbutamol were 11.2, -14.6 and -35.7% respectively, compared to placebo. There was a linear relationship between the magnitude of bronchoconstriction and the between-treatment differences in AUC0-40 FEV1. Increasing bronchoconstriction conferred greater susceptibility to the effects of bronchodilator tolerance.

House dust mite allergen levels in university student accommodation in Dunedin.

AIM: To quantify the levels of Dermatophagoides pteronyssinus (Der p1) in different university student accommodation in Dunedin, and to assess relationships with housing characteristics and housekeeping practices. METHODS: Dwellings (n=178) were randomly selected from a database of first year university students in Dunedin. Dust samples were collected from both bed and the bedroom floor by standardised procedures. Der p1 levels were quantified by monoclonal antibody ELISA techniques. Details of housing characteristics, occupancy and housekeeping practices were obtained by questionnaire. RESULTS: Geometric mean (95% confidence intervals) Der p1 allergen levels from bedroom floors were: family homes (n=61) 5.58 (3.73-8.36) microg/g; student flats (n=43) 3.89 (2.49-6.07) microg/g; halls of residence (n=74) 0.26 (0.16-0.43) microg/g. Der p1 allergen levels from beds were: family homes 15.85 (9.78-26.57) microg/g; student flats 10.5 (6.41-17.19) microg/g; halls of residence 3.25 (2.33-4.54) microg/g. In all accommodation lower levels of Der p1 were found on the floor compared to the bed (p<0.005). Halls of residence had significantly lower Der p1 levels in both bed and floor (p<0.0005). Higher levels of Der p1 were associated with longer duration of occupancy, a history of condensation or mold in the accommodation, failure to use a hot wash for sheets, mattress age greater than one year and infrequent vacuuming of the bedroom floor. CONCLUSIONS: Wide variations in Der p1 levels were observed between different forms of student accommodation. Higher levels of Der p1 are found in family homes than in student flats or halls of residence.