Population Data Centre Profiles: Centre for Data Linkage

The Centre for Data Linkage (CDL) was established at Curtin University, Western Australia, to develop infrastructure to enable cross-jurisdictional record linkage in Australia. The CDL’s operating model makes use of the ‘separation principle’, with content data typically provided to researchers directly by the data custodian; jurisdictional linkage where available are used within the linkage process. Along with conducting record linkage, the team has also invested in establishing a research programme in record linkage methodology and in developing modern record linkage software which can handle the size and complexity of today’s workloads. The Centre has been instrumental in the development of practical methods for privacy-preserving record linkage, with this methodology now regularly used for real-world linkages. While the promise of a nation-wide linkage system in Australia has yet to be met, distributed models provide a potential solution.

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis

BACKGROUND

The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool.

METHODS

Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals.

RESULTS

We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32-0.77); P<0.01], but no difference in complication rates [OR 1.02 (0.88-1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62-0.92); P<0.01; I²=87%] and reduced complication rates [OR 0.73 (0.61-0.88); P<0.01; I²=89%).

CONCLUSIONS

Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine.

Effect of nicotine replacement therapy on mortality, delirium, and duration of therapy in critically ill smokers: a systematic review and meta-analysis

Nicotine replacement therapy is widely used in critically ill smokers and its effect on delirium, mortality and duration of intensive care unit (ICU) admission is unknown. The aims of this review were to determine whether the management of nicotine withdrawal with nicotine replacement therapy reduces delirium, mortality or length of stay in critically ill smokers in ICU. The primary outcome was incidence of author-defined ICU delirium. Secondary outcomes were ICU or hospital mortality, ICU-free days at day 28, and ICU or hospital length of stay. We conducted a systematic review and meta-analysis of the data sources MEDLINE, EMBASE, CINAHL, and the Cochrane Database of Systematic Reviews for randomised controlled trials and observational studies. Clinical trials, observational studies and systematic reviews comparing nicotine replacement therapy with placebo or no treatment were included. Case reports, case series, non-systematic reviews and studies that involved children were excluded. Eight studies were eligible (n=2,636) for inclusion in the data synthesis. In a meta-analysis of observational studies, nicotine replacement therapy was associated with increased delirium (three studies; n=908; I²=0%; finite element method: odds ratio 4.03 [95% confidence interval 2.64, 6.15]; P <0.001). There was no difference in ICU mortality (three studies; n=1,309; P=0.10, I²=44%; finite element method: odds ratio 0.58; 95% confidence intervals 0.31-1.10) and hospital mortality or 28-day ICU-free days. In the absence of high-quality data, nicotine replacement therapy cannot currently be recommended for routine use to prevent delirium or to reduce hospital or ICU mortality in critically ill smokers.

Dose Estimation for a Study of Nuclear Workers in France, the United Kingdom and the United States of America: Methods for the International Nuclear Workers Study (INWORKS)

In the framework of the International Nuclear Workers Study conducted in France, the UK and the U.S. (INWORKS), updated and expanded methods were developed to convert recorded doses of ionizing radiation to estimates of organ doses or individual personal dose equivalent [H(p)(10)] for a total number of 308,297 workers, including 40,035 women. This approach accounts for differences in dosimeter response to predominant workplace energy and geometry of exposure and for the recently published ICRP report on dose coefficients for men and women separately. The overall mean annual individual personal dose equivalent, including zero doses, is 1.73 mSv [median = 0.42; interquartile range (IQR): 0.07, 1.59]. Associated individual organ doses were estimated. INWORKS includes workers who had potential for exposure to neutrons. Therefore, we analyzed neutron dosimetry data to identify workers potentially exposed to neutrons. We created a time-varying indicator for each worker, classifying them according to whether they had a positive recorded neutron dose and if so, whether their neutron dose ever exceeded 10% of their total external penetrating radiation dose. The number of workers flagged as being exposed to neutrons was 13% for the full cohort, with 15% of the cohort in France, 12% of the cohort in the UK and 14% in the U.S. We also used available information on in vivo and bioassay monitoring to identify workers with known depositions or suspected internal contaminations. As a result of this work, information is now available that will allow various types of sensitivity analyses.

Two-year outcomes of "treat and extend" intravitreal therapy for neovascular age-related macular degeneration

PURPOSE

To report 24-month outcomes of anti-vascular endothelial growth factor (VEGF) therapy for treatment-naïve eyes with neovascular age-related macular degeneration (nAMD) using a treat and extend treatment regimen in routine clinical practice.

DESIGN

Database observational study.

PARTICIPANTS

We included treatment-naïve eyes receiving predominantly ranibizumab for nAMD in routine clinical practice treated using a treat and extend regimen that were tracked in the Fight Retinal Blindness observational registry.

METHODS

A cohort of eyes treated by practitioners using exclusively a treat and extend regimen was extracted from the Fight Retinal Blindness observational registry.

MAIN OUTCOME MEASURES

Change in visual acuity (VA) over 2 years and number of injections and visits.

RESULTS

Data from 1198 eyes from 1011 patients receiving anti-VEGF therapy using a treat and extend regimen for treatment-naïve nAMD between January 2007 and December 2012 and with 24-month follow-up were included in the analysis. Mean VA increased by +5.3 logarithm of the minimum angle of resolution letters from 56.5 letters (20/80+1) at initial visit to 61.8 (20/60+2) letters at 24 months. Mean VA gains improved and number of injections increased with successive years from +2.7 letters for eyes commencing in 2007 after a mean of 9.7 injections in 2 years, to +7.8 letters for eyes commencing in 2012 after a mean of 14.2 injections over 2 years. The proportion of eyes with VA >20/40 increased from 27% when starting treatment to 45% after 24 months; the proportion with vision of <20/200 remained unchanged (13% initial, 11% at 24 months). Of the included eyes, 90.5% avoided a vision loss of ≥15 letters. There was an overall mean of 13.0 injections over the 24 months, 7.5 injections in the first year and 5.5 in the second year, with a mean of 14.8 clinic visits.

CONCLUSIONS

These data indicate that eyes managed in routine clinical practice with a treat and extend regimen can achieve good visual outcomes while decreasing the burden of treatments and clinic visits.

Pre-exercise screening and health coaching in CHD secondary prevention: a qualitative study of the patient experience

Secondary prevention programmes can be effective in reducing morbidity and mortality from coronary heart disease (CHD). In particular, UK guidelines, including those from the Department of Health, emphasize physical activity. However, the effects of secondary prevention programmes with an exercise component are moderate and uptake is highly variable. In order to explore patients' experiences of a pre-exercise screening and health coaching programme (involving one-to-one consultations to support exercise behaviour change), semi-structured telephone interviews were undertaken with 84 CHD patients recruited from primary care. The interviews focused on patients' experiences of the intervention including referral and any recommendations for improvement. A thematic analysis of transcribed interviews showed that the majority of patients were positive about referral. However, patients also identified a number of barriers to attending and completing the programme, including a belief they were sufficiently active already, the existence of other health problems, feeling unsupported in community-based exercise classes and competing demands. Our findings highlight important issues around the choice of an appropriate point of intervention for programmes of this kind as well as the importance of appropriate patient selection, suggesting that the effectiveness of health coaching may be under-reported as a result of including patients who are not yet ready to change their behaviours.

Mortality and cancer registration experience of the Sellafield workers known to have been involved in the 1957 Windscale accident: 50 year follow-up

This paper studies the mortality and cancer morbidity of the 470 male workers involved in tackling the 1957 Sellafield Windscale fire or its subsequent clean-up. Workers were followed up for 50 years to 2007, extending the follow-up of a previously published cohort study on the Windscale fire by 10 years. The size of the study population is small, but the cohort is of interest because of the involvement of the workers in the accident. Significant excesses of deaths from diseases of the circulatory system (standardised mortality ratio (SMR) = 120, 95% CI = 103-138; 194 deaths) driven by ischaemic heart disease (IHD) (SMR = 133, 95% CI = 112-157, 141 deaths) were found when compared with the population of England and Wales but not when compared with the population of Northwest England (SMR = 105, 95% CI = 90-120 and SMR = 115, 95% CI = 97-136 respectively). When compared with those workers in post at the time of the fire but not directly involved in the fire the mortality rate from IHD among those involved in tackling the fire was raised but not statistically significantly (rate ratio (RR) = 1.11, 95% CI = 0.92-1.33). A RR of 1.11 is consistent with an excess relative risk of 0.65 Sv(-1) as reported in an earlier study of non-cancer mortality in the British Nuclear Fuels plc cohort of which these workers are a small but significant part. There was a statistically significant difference in lung cancer mortality (RR = 2.18, 95% CI = 1.05-4.52) rates between workers who had received higher recorded external doses during the fire and those who had received lower external doses. Comparison of the mortality rates of workers directly involved in the accident with workers in post, but not so involved, showed no significant differences overall. On the basis of the use of a propensity score the average effect of involvement in the Windscale fire on all causes of death was - 2.13% (se = 3.64%, p = 0.56) though this difference is not statistically significant. The average effect of involvement in the Windscale fire was - 5.53% (se = 3.81, p = 0.15) for all cancers mortality and 6.60% (se = 4.03%, p = 0.10) for IHD mortality though neither figure was statistically significant. This analysis of the mortality and cancer morbidity experience of those Sellafield workers involved in the 1957 Windscale fire does not reveal any measurable effect of the fire upon their health. Although this study has low statistical power for detecting small adverse effects, due to the relatively small number of workers, it does provide reassurance that no significant health effects are associated with the 1957 Windscale fire even after 50 years of follow-up.

Primary and long-term stability of a short-stem hip implant

The new generation short-stem hip implants are designed to encourage physiological-like loading, to minimize stress—strain shielding and therefore implant loosening in the long term. As yet there are no long-term clinical studies available to prove the benefits of these short-stem implants. Owing to this lack of clinical data, numerical simulation may be used as a predictor of longer term behaviour. This finite element study predicted both the primary stability and long-term stability of a short-stem implant. The primary implant stability was evaluated in terms of interface micromotion. This study found primary stability to fall within the critical threshold for osseointegration to occur. Longer term stability was evaluated using a strain-adaptive bone remodelling algorithm to predict the long-term behaviour of the bone in terms of bone mineral density (BMD) changes. No BMD loss was observed in the classical Gruen zones 1 and 7 and bone remodelling patterns were comparable with hip resurfacing results in the literature.

A retrospective case note review of deceased recipients of vCJD-implicated blood transfusions

BACKGROUND

To date, four instances of probable transfusion-transmission of variant Creutzfeldt-Jakob disease (vCJD) infection have been described, and surviving recipients of vCJD-implicated blood components have been informed that they may be 'at risk' of vCJD. Nearly two-thirds of all recipients of vCJD-implicated blood components are deceased, and many died before the vCJD risk was known. The primary aim of this study was to determine retrospectively whether there was evidence that any of the other deceased recipients of vCJD-implicated blood components had any clinical signs or symptoms suggestive of vCJD in life. In addition, pathological material from recipients, stored at the time of surgery or autopsy, was sought to allow testing for evidence of vCJD infection. A secondary aim of the study was to obtain information on invasive healthcare procedures undertaken on recipients following the transfusion to identify the potential for onward transmission of infection.

METHODS

A retrospective review of medical case notes of deceased recipients of vCJD-implicated blood components was carried out, and relevant information was extracted. In cases undergoing post-mortem, details of the findings were obtained.

RESULTS

The medical case notes of 33 (83%) deceased recipients of vCJD-implicated blood components, not already known to be infected with vCJD, were reviewed. The median age of recipients was 68 years (interquartile range 57-79 years). Almost half (16) were male. The median time from transfusion to death was 175 days (interquartile range 43-701 days). Most (66%) recipients died in hospital. None of the recipients had documented evidence of clinical signs or symptoms suggestive of vCJD. Only two recipients, both of whom died within a year of transfusion, underwent autopsy examination. Neither brain nor peripheral lymphoreticular tissue was available from either recipient, and pathological material was unavailable from any of the other deceased recipients. Almost half of all recipients underwent at least one invasive healthcare procedure post-transfusion.

CONCLUSIONS

A retrospective review of the medical case notes of the deceased recipients of vCJD-implicated blood components found no evidence that any further cases expressed clinical signs or symptoms suggestive of vCJD during life, but only four of the recipients survived for more than 5 years post-transfusion.

Mortality experience of male workers at a UK tin smelter

BACKGROUND

Between 1937 and 1991, Capper Pass and Sons Limited operated a tin smelter complex in North Humberside, UK, at which employees were potentially exposed to a number of substances, including lead, arsenic, cadmium and natural series radionuclides. Decommissioning and site clearance continued until 1995. Between 1967 and 1995 the company was a subsidiary of Rio Tinto plc.

AIMS

The aim was to identify any significant excess, or deficits, in mortality among former employees that might be attributable to factors associated with occupation.

METHODS

We defined a cohort of 1462 males who had been employed for at least 12 months between 1/11/1967 and 28/7/1995, followed-up through to 31/12/2001. The mortality of the cohort was compared against that expected for both national and regional populations.

RESULTS

Mortality from all causes and all cancers did not differ from that expected. Mortality from ischaemic heart disease showed a deficit and mortality from lung cancer showed a statistically significant excess. Mortality from smoking related diseases other than lung cancer showed a non-significant deficit.

CONCLUSIONS

The pattern of lung cancer mortality is consistent with the hypothesis that the risk of lung cancer has been enhanced by occupational exposure to one or more carcinogens, the effect of which diminishes with time since exposure. The deficit in ischaemic heart disease may be attributed to a protective effect from manual labour. The results provide no evidence for attribution of other excess or deficits in mortality to factors associated with employment.

Mortality and cancer morbidity experience of female workers at the British Nuclear Fuels Sellafield plant, 1946-1998

BACKGROUND

Studies of nuclear workers have focused mainly on the experience of male workers. To date, little has been published specifically on the experience of female workers in the nuclear industry.

METHODS

We report on the mortality, cancer morbidity, and tracing experience of the 6,376 females ever employed at the British Nuclear Fuels Ltd. plant at Sellafield to the end of 1998. These workers have accumulated 142,337 person-years of experience.

RESULTS

Radiation workers were exposed to low doses of radiation. No statistically significant associations were noted between mortality or cancer morbidity and cumulative assessed organ-specific internal plutonium dose or cumulative external whole body radiation dose overall, or for any of the individual disease groupings examined. The power of the study was insufficient to detect the risks indicated in other radiation studies.

CONCLUSION

This study offers reassurance that there is no detrimental effect on the health of the female workers from occupational exposures at Sellafield. Am. J. Ind. Med. 44:653-663, 2003.

The accessibility of computer-based health information for patients: kiosks and the web

The Internet is a rich source of health information but it is not as accessible as many claim. This paper brings together three projects to illustrate technical and cost barriers and some options to overcome them. (1) A survey amongst a representative sample of 180 patients in rural Spain showed a marked age gradient in computer access. None over the age of 50 had, and less than 10% planned, access to the Internet whereas a quarter were prepared to use health centre based touchscreen kiosks. (2) Half the commonly used search engines did not include the two most relevant websites for Glasgow colorectal cancer patients in the first ten documents listed, showing the difficulty facing patients in finding relevant information. Selection of information would help patients avoid being overwhelmed with information. (3) One method to improve accessibility is to download websites to kiosks but two projects showed that considerable work is required to reformat the information. Public access computing, such as kiosks, could help make the Internet more accessible. We discuss whether Web sites which structure their information according to method of access, place and person provide a way forward.

Trends in hospitalization and mortality from rotavirus disease in New Zealand infants

BACKGROUND

Rotavirus illness is associated with significant morbidity and mortality worldwide. We have examined trends in diarrheal disease in New Zealand children to determine the disease burden attributable to rotavirus and to estimate the proportion of hospitalizations preventable by vaccination.

METHODS

Hospital admissions data and laboratory records for 1994 to 1996, were obtained for children 0 to 4 years at four sites (serving -60% of the New Zealand population). Rotavirus disease burden was estimated using combined admissions and laboratory data. Severity of disease was estimated in a sample of 150 hospitalizations for rotavirus diarrhea, and the proportion of vaccine-preventable admissions was extrapolated. Mortality attributed to diarrheal causes was determined from national records for 1974 to 1993.

RESULTS

Between 1994 and 1996, 4436 children <5 years of age were hospitalized with diarrhea (1047/100000 children per year). Admissions associated with rotavirus were estimated at 1522 to 1535 (315 to 362/100000 annually). Infants between 6 and 17 months were most commonly affected (42% of all cases). More male children than female children were hospitalized (P < 0.001) and mean length of stay was calculated as 1.51 days (SD 2.35). Disease severity scoring revealed that 61.3 and 38.0% of admissions reviewed were severe and very severe, respectively. Deaths from diarrheal causes numbered 138 among children 0 to 4 years old for the 20-year period 1974 to 1993, with 18 deaths occurring between 1984 and 1993 (10 years).

CONCLUSION

Current vaccines control severe disease, suggesting that 72% of cases reviewed would be eligible for prevention. A full cost effectiveness analysis is required to demonstrate anticipated benefits of vaccination.

Extracapsular cataract surgery in Vietnam: a 1 year follow-up study

PURPOSE

Unoperated cataract is the leading cause of blindness in the developing world. Many developing countries now use extracapsular cataract extraction (ECCE) with intra-ocular lens insertion (IOL) in their cataract blindness-prevention programmes. To date, little research has been directed at visual outcomes and complication rates of ECCE/IOL surgery in developing countries.

METHODS

We conducted a follow-up study of 155 eyes approximately 12 months after ECCE/IOL surgery by eight local eye surgeons in Central Vietnam. We report the findings for the 144 eyes (93%) successfully reviewed. All subjects underwent manual ECCE with insertion of a three-piece posterior chamber IOL. All eyes were also assessed for the presence and severity of posterior capsule opacification (PCO) using a newly developed grading system.

RESULTS

Overall, 110 eyes (75%) had uncorrected visual acuities > or = 6/24 and 107 eyes (74%) had best spherically corrected visual acuities > or = 6/18. Some degree of PCO was found in 40% of eyes, but was graded as visually significant in only 4% of eyes. No major sight-threatening complications were noted. A portable neodymium:yttrium aluminium garnet (Nd:YAG) laser was used to perform capsulotomies on all eyes with visually significant PCO. There were no laser complications noted.

CONCLUSIONS

At approximately 1 year after ECCE/IOL, the visual outcomes for subjects in this cohort were favourable and complication rates were low. Posterior chamber opacification was not a major cause of vision impairment in this cohort. Portable Nd:YAG lasers may provide an effective solution to the problem of visually significant PCO occurring in developing countries as a late complication of extracapsular surgery. These findings support an increasing role for ECCE/PCIOL surgery by trained local eye surgeons in developing countries.

Modern surgery for global cataract blindness: preliminary considerations

Unoperated cataract in the developing world remains ophthalmology's major unsolved problem. Recent developments have brought into question the assumptions of those who have thought that extracapsular surgery with implantation of a posterior chamber intraocular lens is an unrealistic approach to the treatment of global cataract blindness. High-quality 1-piece posterior chamber intraocular lenses are being manufactured locally for approximately $10 each. Most ophthalmologists can be trained to perform extracapsular surgery in a 1-month course. This process is particularly effective if outstanding local surgeons receive intensive training to become instructors. While the incidence and treatment of posterior capsule opacification requires further study, the development of a low-cost YAG laser may be a solution. Imaginative ways to recover costs will need to be developed if the staggering prevalence of cataract blindness is to be effectively addressed. The improved result of modern surgery may make patients more willing to pay for their operation.

Traumatic retinopathy resembling acute macular neuroretinopathy

BACKGROUND

Acute macular neuroretinopathy (AMNR) is an uncommon disease of uncertain aetiology. We report on four males who developed unilateral changes following trauma which closely resembled acute macular retinopathy.

METHODS

Retrospective review of selected cases.

RESULTS

Four male patients developed a central or paracentral scotoma immediately or soon after an accident in which they suffered moderately severe bodily injury without direct ocular trauma. Vision was reduced in three patients. All four patients had characteristic well-circumscribed, dark macular lesions best seen using red-free light. The lesions cleared slowly in the two cases who returned for review.

CONCLUSIONS

A picture that closely resembles AMNR may be seen after trauma. The mechanism may involve a sudden rise in ocular venous pressure. This may be an unrecognized cause of visual loss after non-ocular trauma which may be regarded as functional. The subtle retinal lesions may be overlooked unless the fundi are examined in red-free light and the macular dark areas are compared.

Barrier activity of fractionated human serum

PURPOSE

Breakdown of the blood-retinal barrier is a major cause of visual loss in diseases such as diabetic retinopathy, age-related macular degeneration and retinal vein occlusion.

METHODS

Human serum, fractionated by gel filtration, was screened for factors that enhance barrier activity by measuring electrical resistance across monolayers of human umbilical vein endothelial cells.

RESULTS

Two peaks of barrier-enhancing activity were detected. The larger peak was broad, contained a preponderance of albumin and increased barrier activity to 183% of controls. The barrier-enhancing properties of the larger peak, however, appeared to be associated with proteins in general and not just albumin. The fractions associated with elution of the larger peak induced maximal increase in resistance in under 1 h, relative to controls. The smaller peak was associated with molecular weights much smaller than those of proteins.

Spatial cognition in language-impaired children

Limited research evidence is available concerning the spatial abilities of children with specific language impairments. This paper reports a study of the ability of such children to use plan drawings. The participants were 23 language-impaired (LI) children (12 from special boarding schools, 11 from language units within mainstream primary schools), whose performance was compared with that of 23 non-language-impaired (NLI) children. The children were matched for age, their overall age range being between 7;0-11;11 (mean age 8;6). Tasks involved the production and utilisation of plan drawings of a model house. With one exception, results indicated that the LI children showed no deficit in ability on such tasks, and indeed out-performed their NLI peers on many of them. Implications of these findings are discussed.

Interferon-alpha 2b inhibits proliferation of human Tenon's capsule fibroblasts

To evaluate the potential of interferon-alpha 2b (IFN-alpha) as an antifibrotic treatment after glaucoma filtering surgery, we studied its ability to inhibit mitogen-induced proliferation of human Tenon's capsule fibroblasts in vitro, as shown by [3H]-thymidine incorporation. IFN-alpha inhibited fetal calf serum-induced proliferation in a dose-dependent manner in concentrations ranging from 10 to 10,000 IU/ml (P < 0.001). Inhibition was also found when IFN-alpha was added prior to the mitogen (P = 0.001); this inhibitory effect lasted at least 3 days. We suggest that IFN-alpha deserves further evaluation as a possible agent for the control of ocular fibrosis.

Haemophilus influenzae type b disease in Auckland children 1981-87

Haemophilus influenzae type b invasive disease was reviewed in the Auckland paediatric population. A total of 205 episodes were confirmed by sterile cavity culture in 203 patients under 15 years of age over a seven year period. The incidence of invasive disease was 14/100,000/year in those under 15 years and 41/100,000/year in under 5 year olds. The age range was from 1 month to 11 years, with 91% under 5 years and 64% under 2 years. Most cases were due to meningitis (63%). Other diseases included epiglottitis, pneumonia, cellulitis, arthritis, and occult bacteraemia. There was only one fatality. Beta lactamase production was found in 9% of meningeal isolates. Recently a new conjugated haemophilus vaccine has been licensed in the United States for use in children 18 months and older. Consideration should be given to introducing this vaccine in New Zealand.