Biomedical subjects

Katrina Spilsbury

Publications and source records attributed to Katrina Spilsbury.

9 recordsLinked to original sources

PubMed2006

Length of comorbidity lookback period affected regression model performance of administrative health data.

BACKGROUND AND OBJECTIVE: The impact of different comorbidity ascertainment lookback periods on modeling posthospitalization mortality and readmission was examined. METHODS: Index cases comprised medical (n = 326,456) and procedural (n = 349,686) patients with a hospital admission from 1990-1996. Administrative hospital data were extracted for 102 comorbidities, ascertained at index admission and for 1-, 2-, 3-, and 5-year lookback periods. Deaths and readmissions were identified within 12 months and 30 days of separation, respectively. Hierarchically nested and nonnested Cox regressions as well as Receiver Operator Characteristic Area Under the Curve (ROC-AUC) were used to determine model-fit and predictive ability of lookback period models. RESULTS: The 1-year lookback period provided the best model-fit for both patient groups when modeling mortality. A similar model-fit was seen at index admission for procedural but not medical patients. The superior readmission model employed 5 years of lookback for both patient groups. With one exception, all lookback period models were superior to those abstracting comorbidity from index admission only. Similar results were evident from ROC-AUC, although greater predictive ability was seen with modeling of mortality (0.847-0.923) compared with readmission (0.593-0.681). CONCLUSION: The explanatory power of regression models, when adjusting for comorbidity, is influenced by length of lookback, outcome investigated and clinical subgroup. Shorter periods (approximately 1 year) appear appropriate for modeling posthospitalization mortality, whereas longer lookback periods are superior for readmission outcomes.

Cohort Studies↗

PubMed2006

Decreasing rates of middle ear surgery in Western Australian children.

OBJECTIVE: To investigate temporal, social, demographic, and health care utilization factors associated with myringotomy with ventilation tube insertion (MVTI) in Western Australian (WA) children. DESIGN: Observational retrospective population-based cohort study using hospital administrative data. SETTING: All WA hospitals. PARTICIPANTS: A total of 53 673 children younger than 15 years who underwent surgery for MVTI in the period 1981-2004. MAIN OUTCOME MEASURES: Age-specific incidence rates and incidence rate ratios. RESULTS: The rate of MVTI in children younger than 15 years peaked in 1997 at 6.7 per 1000 person-years and decreased to 5.6 per 1000 person-years by 2004. Based on 2004 rates, 8.4% of WA children will undergo at least 1 MVTI procedure before reaching age 15 years. The rate of MVTI was 37% lower in Indigenous children, and the procedures were performed at an older age compared with non-Indigenous children. Higher rates of MVTI were associated with areas of higher economic resources, lower education and occupation status, and living in metropolitan areas. CONCLUSIONS: The rate of MVTI in WA is showing evidence of a decline, even among children younger than 5 years. There remains an issue regarding equity of access to care for Indigenous children. Increasing parental economic resources may be associated with higher rates of MVTI independent of educational status.

Adolescent↗

PubMed2005

Subsequent surgery after initial breast conserving surgery: a population based study.

BACKGROUND: In line with current Australian early breast cancer management guidelines, more women are having breast conserving surgery to treat breast cancer when appropriate. Some women will undergo further surgery because of involved margins, early local relapse, or other factors including patient choice. The aim of this study was to investigate whether socio-economic, demographic or hospital factors were associated with the risk of re-excision or subsequent mastectomy. METHODS: A record linkage population-based study on 12 711 women diagnosed with breast cancer in Western Australia from 1982 to 2000 who underwent breast surgery within 12 months of diagnosis was performed. Logistic regression was used to identify social, demographic and hospital factors associated with the risk of undergoing further surgery following initial breast conserving surgery. RESULTS: The proportion of women undergoing initial breast conserving surgery doubled from 33% in 1982-1985 to 72% in 1998-2000. The proportion of women who underwent further surgery following initial breast conserving surgery decreased from 50 to 30% over the same period. The risk of re-excision or subsequent mastectomy was between 2.4 (95% CI 1.7-3.4) and 5.0 (95% CI 3.4-7.4) times greater if initial surgery was performed in a non-metropolitan hospital compared to Perth hospitals. Younger women were between 1.7 (95% CI 1.4-2.0) and 2.1 (95% CI 1.5-3.0) times more likely to undergo re-excisions compared to women aged 50-64 years of age. CONCLUSIONS: Young women and women initially treated in non-metropolitan hospitals were at an increased risk of re-excision or a subsequent mastectomy following initial breast conserving surgery to treat breast cancer. Efforts need to be directed towards improving specialist health services outside of Perth if women continue to be treated for breast cancer in non-metropolitan hospitals.

Adult↗

PubMed2005

Long-term survival outcomes following breast cancer surgery in Western Australia.

BACKGROUND: Mortality rates from breast cancer are stabilizing or falling in many developed countries including Australia, however, survival outcomes are known to vary by social, demographic and treatment related factors. The aim of the present study was to investigate how hospital, social and demographic factors were associated with survival outcomes from surgically treated breast cancer for all women living in Western Australia. METHODS: The WA Data Linkage System was used to access hospital morbidity, death and cancer information for all women diagnosed with invasive breast cancer in Western Australia 1982-2000. Relative survival and Cox proportional hazards regression analyses were used to identify social, demographic and hospital factors associated with an increased risk of dying from breast cancer or dying from any cause. RESULTS: Survival outcomes improved in all women diagnosed in more recent calendar periods. However, a significantly increased risk of dying was observed for women who underwent initial surgical treatment in regional public hospitals outside of the state capital, Perth. Consistent with other reports, women aged greater than 80 years and younger than 35 years at diagnosis also had poorer survival outcomes. Residential location, socioeconomic status and race were not associated with survival after adjusting for treatment, health and hospital related factors. CONCLUSIONS: Despite overall improvements in survival of women diagnosed with breast cancer in Western Australia, initial surgical treatment in public hospitals outside of Perth was associated with significantly poorer outcomes.

Adult↗

PubMed2004

Unequal access to breast-conserving surgery in Western Australia 1982-2000.

BACKGROUND: The purpose of the present study was to examine the effects of demographic, locational and social disadvantage and the possession of private health insurance in Western Australia on the likelihood of women with breast cancer receiving breast-conserving surgery rather than mastectomy. METHODS: The WA Record Linkage Project was used to extract all hospital morbidity, cancer and death records of women with breast cancer in Western Australia from 1982 to 2000 inclusive. Comparisons between those receiving breast-conserving surgery and mastectomy were made after adjustment for covariates in logistic regression. RESULTS: Younger women, especially those aged less than 60 years, and those with less comorbidity were more likely to receive breast-conserving surgery (BCS). In lower socio-economic groups, women were less likely to receive BCS (OR 0.73; 95% CI 0.60-0.90). Women resident in rural areas tended to receive less BCS than those from metropolitan areas (OR 0.84; 95% CI 0.55-1.29). Women treated in a rural hospital had a reduced likelihood of BCS (OR 0.74; 95% CI 0.61-0.89). Treatment in a private hospital reduced the likelihood of BCS (OR 0.70; 95% CI 0.54-0.90), while women with private health insurance were much more likely to receive BCS (OR 1.39; 95% CI 1.08-1.79). CONCLUSION: Several factors were found to affect the likelihood of women with breast cancer receiving breast-conserving surgery, in particular, women from disadvantaged backgrounds were significantly less likely to receive breast-conserving surgery than those from more privileged groups.

Female↗

PubMed2004

Oestrogen receptors revisited: long-term follow up of over five thousand breast cancer patients.

BACKGROUND: The oestrogen receptor status of a breast tumour predicts the response to hormonal treatment and is an important prognostic marker; women with oestrogen receptor positive tumours having a better short-term survival outcome. METHODS: Kaplan-Meier estimates and Cox proportional hazard model were used to estimate the association between oestrogen receptor levels and long-term breast cancer-specific survival outcomes in 5735 women diagnosed with breast carcinoma from 1970 to 1997 in Western Australia. Further analysis was performed on a subset of women for whom biochemical and tumour characteristics were also available. RESULTS: Five-year breast cancer-specific survival estimates for women with oestrogen receptor positive tumours was 0.85 (95% CI 0.84-86) compared to 0.72 (95% CI 0.70-74) for women with oestrogen receptor negative tumours. The relative survival advantage of an oestrogen positive tumour over oestrogen negative tumours disappeared by the fourth year (0.8, 95% CI 0.6-1.0). Conditional upon surviving 5 years, long-term breast cancer-specific survival was better for women with oestrogen receptor and progesterone receptor negative tumours compared to other women (log rank test P-value <0.05). CONCLUSION: Despite an earlier survival advantage for women diagnosed with oestrogen receptor positive tumours, after 5 years of survival, women with oestrogen receptor negative and progesterone receptor negative tumours had better long-term survival outcomes from breast cancer compared to other women.

Breast Neoplasms↗

PubMed2003

Circumcision for phimosis and other medical indications in Western Australian boys.

OBJECTIVE: To investigate the incidence rate of circumcision for phimosis and other medically indicated reasons in Western Australian boys from 1 January 1981 to 31 December 1999. DESIGN AND SETTING: A population-based incidence study using hospital discharge data of all circumcisions performed in all WA hospitals during the study period. MAIN OUTCOME MEASURES: Changes in the incidence rate of circumcision for medically indicated reasons. RESULTS: The rate of medically indicated circumcisions increased in boys aged less than 15 years during the study period. Phimosis was the most common medical indication for circumcision in all age groups. The rate of circumcision associated with phimosis was eight times that associated with balanoposthitis and 21 times that of balanitis xerotica obliterans. Boys aged less than five years had the highest rate of circumcision to treat phimosis, at 4.6 per 1000 person-years, representing about 300 circumcisions per year. Boys aged less than five years living in country areas were 1.5 times more likely to be circumcised for phimosis than boys living in metropolitan Perth. CONCLUSION: The rate of circumcision to treat phimosis in boys aged less than 15 years is seven times the expected incidence rate for phimosis. Many boys are circumcised before reaching five years of age, despite phimosis being rare in this age group.

Adolescent↗

PubMed2003

Routine circumcision practice in Western Australia 1981-1999.

BACKGROUND: Routine neonatal circumcision has declined in most English-speaking countries. The purpose of the present study was to investigate the trends in incidence of routine circumcision in Western Australia and current patterns of the procedure according to sociodemographic factors. METHODS: Hospital morbidity data were used to conduct a population-based study of all circumcisions performed in Western -Australian hospitals during 1981-1999. Medicare insurance rebate statistics were used to estimate the numbers of circumcisions performed outside of hospital on boys <6 months of age between 1994 and 1999. RESULTS: In 1994, 9.8% of boys were circumcised before reaching 6 months of age, falling to 7.9% by 1999. Boys <6 months of age were 3.3 times more likely to undergo a hospital-performed circumcision if they lived in country areas compared with metropolitan Perth. Middle socioeconomic class families were twice as likely to circumcise a son than those in the higher and lower socioeconomic groups. The decreasing circumcision rate in boys <6 months of age was partly offset by an increase in routine circumcisions in boys older than 6 months of age during 1981-1999. CONCLUSION: Circumcision remains a relatively common procedure in Western Australia. Based on total routine circumcision rates in 1999, 10.2% of boys will be circumcised by the time they reach 15 years of age. The routine circumcision rate in boys <6 months is falling in contrast to a rising routine circumcision rate in older boys. Risk factors for a circumcision before 6 months of age include living in country areas and a middle socioeconomic status.

Adolescent↗

PubMed2002

Inhibition of corneal neovascularization by recombinant adenovirus mediated antisense VEGF RNA.

The expression of vascular endothelial growth factor has been strongly implicated in the pathogenesis of conditions leading to inappropriate blood vessel growth in the eye. As such, vascular endothelial growth factor is an attractive target for anti-angiogenic therapies designed to treat neovascular eye diseases. One such therapy, antisense gene therapy, is a technique based on the ability of single-stranded DNA or RNA sequences to alter the expression of targeted genes. Recombinant adenoviruses have demonstrated efficient ocular cell transduction with a high level of transgene production. Cauterization of the normally avascular rat cornea results in a strong neovascular response, making it an ideal animal model for the testing of anti-angiogenic therapies. In this study, a recombinant adenovirus system was assessed for the ability to express biologically relevant antisense RNA to reduce vascular endothelial growth factor expression in a rat model of corneal neovascularization. Recombinant adenovirus constructs expressing short and long antisense and sense vascular endothelial growth factor cDNA, under the control of cytomegalovirus major immediate early promoter or the RNA polymerase III promoter, VA1, were constructed. The expression of short and long antisense RNAs was demonstrated by Northern blot hybridization. All constructs were capable of producing RNA, and the highest level of antisense RNA production was detected in retinal pigment epithelial cells which had been transduced with the longer antisense cDNA construct under the control of the VA1 promoter. This construct was also the most efficient in reducing in vitro vascular endothelial growth factor production (P<0.05) and human endothelial cell proliferation. This construct was subsequently injected into rat eyes 24hr prior to cauterization of the cornea and antisense vascular endothelial growth factor expression was demonstrated by in situ hybridization. The resulting neovascular response was clearly inhibited at 4, 7 and 14 days post-cautery, compared to the control injections which demonstrated an intense neovascular response. Only one out of six eyes injected with the long antisense cDNA construct under the control of the VA1 promoter demonstrated any vascular response to cautery. The reduction in the neovascular response was correlated, with significantly lower amounts of vascular endothelial growth factor protein in the corneas (P=0.006). These observations suggest that the specific down-regulation of vascular endothelial growth factor production is sufficient to reduce the corneal neovascular response and that recombinant adenovirus might be a useful vehicle to produce antisense RNA in situ to down-regulate ocular gene expression.

Adenoviridae↗