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Allan M Z Chang

Publications and source records attributed to Allan M Z Chang.

4 recordsLinked to original sources
PubMed2006

Customised birthweight: coefficients for an Australian population and validation of the model.

BACKGROUND: Published birthweight references in Australia do not fully take into account constitutional factors that influence birthweight and therefore may not provide an accurate reference to identify the infant with abnormal growth. Furthermore, studies in other regions that have derived adjusted (customised) birthweight references have applied untested assumptions in the statistical modelling. AIMS: To validate the customised birthweight model and to produce a reference set of coefficients for estimating a customised birthweight that may be useful for maternity care in Australia and for future research. METHODS: De-identified data were extracted from the clinical database for all births at the Mater Mother's Hospital, Brisbane, Australia, between January 1997 and June 2005. Births with missing data for the variables under study were excluded. In addition the following were excluded: multiple pregnancies, births less than 37 completed week's gestation, stillbirths, and major congenital abnormalities. Multivariate analysis was undertaken. A double cross-validation procedure was used to validate the model. RESULTS: The study of 42,206 births demonstrated that, for statistical purposes, birthweight is normally distributed. Coefficients for the derivation of customised birthweight in an Australian population were developed and the statistical model is demonstrably robust. CONCLUSIONS: This study provides empirical data as to the robustness of the model to determine customised birthweight. Further research is required to define where normal physiology ends and pathology begins, and which segments of the population should be included in the construction of a customised birthweight standard.

Australia↗
PubMed2002

Four-year follow-up of women who were diagnosed to have postpartum urinary retention.

OBJECTIVE: The purpose of this study was to evaluate the long-term prevalence of urinary incontinence in women with postpartum urinary retention. STUDY DESIGN: A telephone interview was conducted by contacting a cohort of 691 women who delivered vaginally 4 years ago, of which 101 women had been diagnosed as having postpartum urinary retention. A structured telephone interview consisted of 9 questions on the possible outcomes of postpartum urinary retention. RESULTS: Of the original cohort of 691 women, 394 women were contacted. Seventy-three women had had postpartum urinary retention, and 321 women had not. In women who had had postpartum urinary retention, the prevalence of the outcome variables were urinary stress incontinence (28.8%), fecal incontinence (2.7%), frequency (39.1%), nocturia (65.2%), urgency (26.1%), urge incontinence (26.1%), and coital incontinence (13%). Analyses showed that there was no significant difference between women with and without urinary retention. CONCLUSION: Women who had had postpartum urinary retention did not have a higher prevalence of urinary stress incontinence.

Female↗
PubMedDate not supplied

Path analysis modeling indicates free transport increases ambulance use for minor indications.

INTRODUCTION: Clinically unnecessary ambulance transport is increasing, diverting limited resources from patients needing ambulance transport. It was anecdotally observed that inappropriate ambulance use increased after abolition of a direct patient cost for ambulance transport. HYPOTHESIS: In July 2003, direct patient fees were abolished in favor of a universally applied ambulance levy, potentially leading to increased ambulance use by patients with low illness acuity and admission rates. METHODS: The influence of age, illness acuity, and need for admission on ambulance use was assessed for 55,397 emergency department attendances in 2002 and 2004. Ambulance users were compared with nonusers in both years and attendances for 2002 compared with 2004 using chi-square test for two groups. Logistic regression provided a multivariate model leading to ambulance use. Path analysis modeling to assess interrelationships between factors associated with ambulance use was developed. RESULTS: Ambulance users in both years were older, had more acute illness, and had greater need for admission compared with nonusers. The odds ratio (OR) of arrival by ambulance in 2004 compared with 2002 was 1.14 (95% confidence interval, [CI], 1.12 to 1.17). In 2002, ambulance users were older (OR, 1.42; 95% CI, 1.40 to 1.43), were more likely to need admission (OR, 2.28; 95% CI, 2.16 to 2.4) and had higher illness acuity (OR, 2.02; 95% CI, 1.94 to 2.09). There was a negative correlation between 2004 and illness acuity. CONCLUSIONS: Ambulance use increased in 2004 after patient transport fees were abolished. Increased use was associated with decreased age, clinical acuity, and admission need. Abolishing direct patient cost stimulates ambulance use, potentially including inappropriate transport. Path analysis to assess the effect of changed funding on ambulance use could be used to the influence of other locally relevant factors contributing to ambulance use.

Adolescent↗