Accuracy of automatic syndromic classification of coded emergency department diagnoses in identifying mental health-related presentations for public health surveillance.

BACKGROUND: Syndromic surveillance in emergency departments (EDs) may be used to deliver early warnings of increases in disease activity, to provide situational awareness during events of public health significance, to supplement other information on trends in acute disease and injury, and to support the development and monitoring of prevention or response strategies. Changes in mental health related ED presentations may be relevant to these goals, provided they can be identified accurately and efficiently. This study aimed to measure the accuracy of using diagnostic codes in electronic ED presentation records to identify mental health-related visits. METHODS: We selected a random sample of 500 records from a total of 1,815,588 ED electronic presentation records from 59 NSW public hospitals during 2010. ED diagnoses were recorded using any of ICD-9, ICD-10 or SNOMED CT classifications. Three clinicians, blinded to the automatically generated syndromic grouping and each other's classification, reviewed the triage notes and classified each of the 500 visits as mental health-related or not. A "mental health problem presentation" for the purposes of this study was defined as any ED presentation where either a mental disorder or a mental health problem was the reason for the ED visit. The combined clinicians' assessment of the records was used as reference standard to measure the sensitivity, specificity, and positive and negative predictive values of the automatic classification of coded emergency department diagnoses. Agreement between the reference standard and the automated coded classification was estimated using the Kappa statistic. RESULTS: Agreement between clinician's classification and automated coded classification was substantial (Kappa = 0.73. 95% CI: 0.58 - 0.87). The automatic syndromic grouping of coded ED diagnoses for mental health-related visits was found to be moderately sensitive (68% 95% CI: 46%-84%) and highly specific at 99% (95% CI: 98%-99.7%) when compared with the reference standard in identifying mental health related ED visits. Positive predictive value was 81% (95% CI: 0.57 - 0.94) and negative predictive value was 98% (95% CI: 0.97-0.99). CONCLUSIONS: Mental health presentations identified using diagnoses coded with various classifications in electronic ED presentation records offers sufficient accuracy for application in near real-time syndromic surveillance.

Trends in notifiable blood lead levels in NSW, 1998-2008.

AIM: In the absence of published statewide notification data, the aim of this study was to analyse trends in notifiable blood lead levels (hereafter referred to as lead poisoning) in NSW from 1998 to 2008, to help inform lead poisoning notification policy. METHODS: NSW blood lead poisoning notification data for 1998-2008 were extracted from the Notifiable Diseases Database and analysed by age, gender and Area Health Service of residence. RESULTS: There were 6000 lead poisoning notifications from 1998 to 2008, with an average annual notification rate of 11.8 per 100 000 population for 1998-2003. This rate declined to an average of 4.0 per 100 000 population in the period 2004-2008. Males accounted for 92% of notifications, and males aged 20-59 years had average notification rates between 20 and 27 per 100 000 population. Children aged 0-4 years had notification rates of 9.3 per 100 000 population in girls and 13.6 per 100 000 population in boys. CONCLUSION: Notification rates have fallen dramatically, however children aged 0-4 years and men are disproportionately represented in lead poisoning notifications.

Relationship between the population incidence of febrile convulsions in young children in Sydney, Australia and seasonal epidemics of influenza and respiratory syncytial virus, 2003-2010: a time series analysis.

BACKGROUND: In 2010, intense focus was brought to bear on febrile convulsions in Australian children particularly in relation to influenza vaccination. Febrile convulsions are relatively common in infants and can lead to hospital admission and severe outcomes. We aimed to examine the relationships between the population incidence of febrile convulsions and influenza and respiratory syncytial virus (RSV) seasonal epidemics in children less than six years of age in Sydney Australia using routinely collected syndromic surveillance data and to assess the feasibility of using this data to predict increases in population rates of febrile convulsions. METHODS: Using two readily available sources of routinely collected administrative data; the NSW Emergency Department (ED) patient management database (1 January 2003 - 30 April 2010) and the Ambulance NSW dispatch database (1 July 2006 - 30 April 2010), we used semi-parametric generalized additive models (GAM) to determine the association between the population incidence rate of ED presentations and urgent ambulance dispatches for 'convulsions', and the population incidence rate of ED presentations for 'influenza-like illness' (ILI) and 'bronchiolitis' - proxy measures of influenza and RSV circulation, respectively. RESULTS: During the study period, when the weekly all-age population incidence of ED presentations for ILI increased by 1/100,000, the 0 to 6 year-old population incidence of ED presentations for convulsions increased by 6.7/100,000 (P < 0.0001) and that of ambulance calls for convulsions increased by 3.2/100,000 (P < 0.0001). The increase in convulsions occurred one week earlier relative to the ED increase in ILI. The relationship was weaker during the epidemic of pandemic (H1N1) 2009 influenza virus.When the 0 to 3 year-old population incidence of ED presentations for bronchiolitis increased by 1/100,000, the 0 to 6 year-old population incidence of ED presentations for convulsions increased by 0.01/100,000 (P < 0.01). We did not find a meaningful and statistically significant association between bronchiolitis and ambulance calls for convulsions. CONCLUSIONS: Influenza seasonal epidemics are associated with a substantial and statistically significant increase in the population incidence of hospital attendances and ambulance dispatches for reported febrile convulsions in young children. Monitoring syndromic ED and ambulance data facilitates rapid surveillance of reported febrile convulsions at a population level.

Annual report: surveillance of adverse events following immunisation in Australia, 2009.

This report summarises Australian passive surveillance data for adverse events following immunisation (AEFI) reported to the Therapeutic Goods Administration (TGA) for 2009, and describes reporting trends over the 10-year period 2000 to 2009. There were 2,396 AEFI records for vaccines administered in 2009, the highest number reported, a 46% increase over the 1,638 in 2008. The increase was almost entirely due to reports related to the introduction of pandemic H1N1 (pH1N1) 2009 influenza vaccine from September 2009 (n = 1,312) largely from the members of the public. The pH1N1 AEFI reporting rate for people aged > or = 18 years was 34.2 per 100,000 administered doses compared with 2.8 for seasonal influenza vaccine. The rates in > or = 65 year-olds were 28.0, 1.6 and 13.3 for pH1N1, seasonal influenza and polysaccharide pneumococcal, respectively. The high reporting rate for pH1N1 vaccine is likely to be at least partly due to enhanced reporting seen for all new vaccines and greater levels of reporting from members of the public in response to the implementation of strategies to encourage reporting, as part of the pH1N1 program. For children < 7 years, AEFI reporting rates in 2009 (14.1 per 100,000 administered doses) were similar to previous years. There were 193 (8%) AEFI reports classified as serious; 6 deaths temporally associated with immunisation were reported but none were judged to have a causal association. As in previous years, the most commonly reported reactions were allergic reaction, injection site reaction, fever, headache, malaise, nausea and myalgia. The most commonly reported reactions following pH1N1 influenza vaccine were allergic reaction (n = 381), headache (n = 289), fever (n = 235), pain (n = 186), nausea (n = 180) and injection site reaction (n = 178). The data within the limitation of passive surveillance provide a reference point for ongoing reporting of trends in AEFI by age group, severity and vaccine type and illustrate the value of the national TGA database as a surveillance tool for monitoring AEFI nationally.

Impact of faxed health alerts on the preparedness of general practitioners during communicable disease outbreaks.

The NSW Department of Health (NSW Health) faxed health alerts to general medical practitioners during measles outbreaks in March and May 2006. We conducted a retrospective cohort study of randomly selected general practitioners (GPs) (1 per medical practice) in New South Wales to investigate the effectiveness of faxing health alerts to GPs during a communicable disease outbreak. Fax transmission data allowed comparison of GPs sent and not sent the measles alert for self-reported awareness and practice actions aimed at the prevention and control of measles. A total of 328 GPs participated in the study. GPs who were sent the alert were more likely to be aware of the measles outbreak (RR 1.18, 95% CI 1.02, 1.38). When analysed by whether a fax had been received from either NSW Health or the Australian General Practice Network, GPs who reported receiving a faxed measles alert were more likely to be aware of the outbreak (RR 2.56, 95% CI 1.84, 3.56), to offer vaccination to susceptible staff (RR 6.46, 95% CI 2.49, 16.78), and be aware of other infection control recommendations. Respondents reported that the faxed alerts were useful with 65% reporting that the alerts had reminded them to consider measles in the differential diagnosis. This study shows that faxed health alerts were useful for preparing GPs to respond effectively to a communicable disease outbreak. The fax alert system could be improved by ensuring that all general practices in New South Wales are included in the faxstream database and that their contact details are updated regularly.

Australia's national Q fever vaccination program.

A nationally funded Q fever vaccination program was introduced in Australia in 2002. The evaluation of this unique program included measures of program uptake, safety, and notification and hospitalisation rates for Q fever pre- and post-program implementation. Program uptake ranged from close to 100% amongst abattoir workers to 43% in farmers. The most commonly reported adverse event was injection site reaction. Q fever notification rates declined by over 50% between 2002 and 2006, particularly in young adult males, consistent with the profile of the abattoir workforce. Hospitalisation data showed similar trends. Available evidence suggests a significant impact of Australia's Q fever vaccination program; such a program merits consideration in other countries with a comparable Q fever disease burden.

Annual report on surveillance of adverse events following immunisation in Australia, 2006.

This report summarises Australian passive surveillance data for adverse events following immunisation (AEFI) reported to the Adverse Drug Reactions Advisory Committee for 2006, and describes reporting trends over the seven-year period 2000 to 2006. There were 779 AEFI records for vaccines administered in 2006. This is an annual AEFI reporting rate of 3.8 per 100,000 population, the lowest since 2002 and a 10% decrease compared with 2005 (869 AEFI records; 4.3 records per 100,000 population). Dose-based AEFI reporting rates in 2006 were 1.9 per 100,000 doses of influenza vaccine for adults aged > or = 18 years, 19.1 per 100,000 doses of pneumococcal polysaccharide vaccine for those aged > or = 65 years and 12.5 per 100,000 doses of scheduled vaccines for children aged < 7 years. Trend data showed transient increases in reporting of AEFI following the introduction of DTPa-IPV combination vaccines in November 2005 for children aged < 7 years. The majority of the 779 AEFI records for 2006 described non-serious events while 11% (n = 85) described AEFIs defined as serious. There was one report of death temporally associated with receipt of dTpa-IPV and typhoid vaccines in an adult with a history of a chronic medical condition. The most frequently reported individual AEFI was injection site reaction in children following a fourth or fifth dose of acellular pertussis-containing vaccine (70 reports per 100,000 doses). The data confirm the low rate of AEFI reported in Australia and demonstrate the ability of the system to detect and investigate signals such as those associated with changes in immunisation programs.

Australia's notifiable diseases status, 2004, annual report of the National Notifiable Diseases Surveillance System.

In 2004, 60 diseases and conditions were nationally notifiable in Australia. States and Territories reported a total of 110,929 cases of communicable diseases to the National Notifiable Diseases Surveillance System (NNDSS): an increase of 4 per cent on the number of notifications in 2003. In 2004, the most frequently notified diseases were sexually transmissible infections (46,762 cases; 42% of total notifications), gastrointestinal diseases (25,247 cases; 23% of total notifications) and bloodborne diseases (19,191 cases; 17% of total notifications). There were 13,206 notifications of vaccine preventable diseases, 6,000 notifications of vectorborne diseases, 1,799 notifications of other bacterial infections (includes, legionellosis, leprosy, meningococcal infections and tuberculosis) and 877 notifications of zoonotic diseases.

Annual report: surveillance of adverse events following immunisation in Australia, 2004.

This report summarises Australian passive surveillance data on adverse events following immunisation (AEFI) for 2004 and describes reporting trends over the five years, 2000 to 2004. AEFIs are notified to the Adverse Drug Reactions Advisory Committee by state and territory health departments, hospitals, doctors and other health providers, vaccine manufactures, and the public. There were 975 AEFI records for vaccines received in 2004. This is an annual AEFI reporting rate of 4.8 per 100,000 population, the lowest since 2000, and a 33 per cent decrease compared with 2003 (1,460 records; 7.1 AEFI records per 100,000 population). Dose-based AEFI reporting rates in 2004 were 1.8 per 100,000 doses of influenza vaccine for adults aged > or = 18 years and 11.8 per 100,000 doses of scheduled vaccines for children aged < 7 years. The majority of records described non-serious events while nine per cent (n = 88) described AEFIs defined as 'serious'. There were no reports of death related to immunisation. The most frequently reported individual AEFI was injection site reaction in children following a fifth dose of an acellular pertussis-containing vaccine (67 reports per 100,000 doses). The marked reduction in the AEFI reporting rate in 2004 coincided with the removal of the fourth dose of acellular pertussis vaccine, due at 18 months of age, from the vaccination schedule in September 2003 and fewer people receiving meningococcal C vaccine through the national catch-up vaccination program for those aged 1-19 years in 2004, compared with 2003. The consistently low reporting rate of serious AEFIs demonstrates the high level of safety of vaccines in Australia.

Age-related risk of adverse events following yellow fever vaccination in Australia.

Reports of six deaths internationally, including one from Australia, plus other cases of severe systemic adverse events following yellow fever (YF) vaccination have raised concern about the safety of YF vaccine, particularly among older vaccinees. We investigated the age-related reporting rates of adverse events following YF vaccination reported to the Australian Adverse Drug Reactions Advisory Committee for the period 1993 to 2002. The reporting rate of systemic adverse events leading to hospitalisation or death was significantly higher among vaccinees aged > or = 65 years [reporting rate ratio (RRR) 8.95, 95% confidence interval (CI) 1.49-53.5] or > or = 45 years (RRR 5.30, 95% CI 1.33-21.2) compared with younger YF vaccinees. The higher reporting rates among older vaccinees are similar to those identified in the United States of America. The data highlight the importance of assessing the destination-specific risk, especially for older travellers to yellow fever endemic areas, and careful monitoring of those who are vaccinated.

Reasons for incomplete immunisation among Australian children. A national survey of parents.

BACKGROUND: Incomplete immunisation among Australian children may be due to parents disagreeing with immunisation rather than medical contraindications or access issues. SETTING AND METHODS: The parents of 1338 children recorded on the ACIR as incompletely immunised were telephoned and interviewed. RESULTS: Of the 462 parents who confirmed their child was incompletely immunised, 270 (58%) disagreed with or were concerned about immunisation; 190 (70%) of these were concerned about vaccine side effects. The disagreeing 270 parents were significantly more likely to be highly educated and have a child with no vaccinations recorded on the ACIR. No vaccinations were recorded on the ACIR for 81% of children of both these parents, and of parents registered as conscientious objectors to immunisation. Together these two groups accounts for 2.5-3.0% of the annual birth cohort. DISCUSSION: In order to achieve the 95% immunisation rates necessary for disease control, tailored approaches to promote immunisation among parents are required.

Effectiveness of the linkage of child care and maternity payments to childhood immunisation.

In 1998, Australia enacted comprehensive national legislation making receipt of the maternity immunisation allowance (MIA) and the child care benefit (CCB) conditional on evidence of age-appropriate immunisation. We assessed the impact of this policy on immunisation status using a nationally representative population-based case-control study of 589 fully immunised controls and 190 incompletely immunised cases, aged 28-31 months. Immunisation status was significantly associated with parent awareness of the MIA (adjusted odds ratio (aOR) = 3.34, 95% CI = 2.28 - 4.91) and CCB (aOR = 2.08, 95% CI = 1.30 - 3.34). Only 31% of the 219 control parents who were receiving the CCB reported that they could continue to afford child care without the assistance of the CCB. The use of legislated financial immunisation incentives for parents appears to be widely accepted among Australian parents and to have had an impact on immunisation uptake. The policy may serve as a model for other comparable countries.

Immunisation coverage in Australia corrected for under-reporting to the Australian Childhood Immunisation Register.

OBJECTIVE: To assess the level of under-reporting to the Australian Childhood Immunisation Register (ACIR) and the resulting underestimation of national immunisation coverage using ACIR data, and to correct national immunisation estimates for under-reporting. METHODS: A national population-based telephone survey was conducted in May-July 2001 of two random samples of children born in 1998 and 1999 who were recorded on the ACIR as incompletely immunised at either 12 months or 24 months of age. Parents were asked whether and when their child had received the vaccinations required to qualify as fully immunised. Survey data were then used to correct ACIR-derived coverage estimates at 12 and 24 months of age. RESULTS: Of 640 surveyed children in the 12-month group, 258 (40%) met the study definition of 'definitely immunised'. This adjusted the ACIR coverage estimate upwards by 2.7% to 94% (95% CI 93.6-94.1). Of 698 surveyed children in the 24-month group, 387 (55%) met the study definition of 'definitely immunised' at the second birthday. Adjusted coverage for doses due by 24 months was 89.8% (95% CI 89.6-90.1), 5% higher than recorded on the ACIR. CONCLUSIONS: Immunisation coverage in Australia for all scheduled vaccines due by 12 months of age is 94% and for all vaccines due by two years of age is almost 90%. The ACIR underestimates coverage by up to 5%. As the ACIR database relies on provider notification, published estimates of immunisation coverage are unlikely to rise significantly above current levels, unless mechanisms are put in place to further improve notification to the ACIR.

Estimating immunisation coverage: is the 'third dose assumption' still valid?

Immunisation coverage is calculated from Australian Childhood Immunisation Register (ACIR) data using the 'third dose assumption'. This assumes that if the third in a series of vaccine doses has been recorded on the ACIR, the previous two doses have been received, whether or not they are recorded. The objectives of this study were to validate the 'third dose assumption', and measure the impact of the assumption on immunisation coverage estimates at 12 months of age. A sample of children born in 1999 and assessed as fully immunised at 12 months of age by applying the 'third dose assumption' were selected from the ACIR. Parents were interviewed by telephone to obtain information about vaccinations not recorded on the ACIR. Based on the survey results, the impact of the 'third-dose assumption' on national coverage estimates at 12 months of age was estimated. Of 219 surveyed children assessed as up-to-date at 12 months of age only by applying the 'third dose assumption', 212 (96.8%) met study criteria of 'definite' immunisation for all unrecorded first and second vaccine doses. Of the remaining seven, six believed all doses had been received, while one confirmed that one dose had been missed. The 'third dose assumption' overestimated coverage by 0.2 per cent, based on criteria for 'definite' immunisation. If the assumption were not used, immunisation coverage at 12 months of age in Australia would have been underestimated by 7 per cent. The 'third dose assumption' is valid and important to use in calculating immunisation coverage from the ACIR. Although ACIR reporting and coverage levels continue to improve, under-reporting of vaccine doses due at two and four months of age persists. The 'third dose assumption' may be applicable to comparable immunisation registries in other countries.

Is low immunisation coverage in inner urban areas of Australia due to low uptake or poor notification?

INTRODUCTION: The Australian Childhood Immunisation Register (ACIR) consistently reveals pockets of lower immunisation coverage in inner urban areas. We investigated whether low uptake or poor notification of immunisation is the main reason for this difference. METHODS: We estimated under reporting by telephone surveying the parents of 640 children recorded as incompletely immunised on the ACIR at 12 months of age. Immunisation status was based on parental report of written records and/or date of receipt. RESULTS: Of the 97 children living in inner urban areas (defined by postcode and population density), 55 (57%) were shown to be 'definitely immunised'. One hundred and thirty-four (53%) of the 253 children in other urban areas were shown to be 'definitely immunised'. Both these groups were significantly more likely to be 'definitely immunised' than the 104 (36%) of 290 children in areas outside capital cities (p < 0.0001). DISCUSSION: Apparent lower immunisation uptake in inner urban areas of Australia may be attributable to reporting error.

Measles vaccination coverage among five-year-old children: implications for disease elimination in Australia.

OBJECTIVES: To (i) assess under-reporting of measles-mumps-rubella (MMR) vaccinations to the Australian Childhood Immunisation Register (ACIR); (ii) estimate MMR coverage among five-year-old children and the proportion immune to measles infection; (iii) identify factors related to non-uptake of MMR vaccination. METHODS: We analysed ACIR data for a birth cohort of approximately 64,000 children aged five years. The parents of a sample of 506 children with no ACIR record for the second MMR vaccination (MMR2), due at four years of age, were interviewed by telephone to assess under-reporting to the ACIR and reasons for non-uptake of MMR vaccination. RESULTS: Parents reported that 22% (n = 111) of the surveyed 506 children had received MMR2 before their fifth birthday, and 42% (n = 214) by approximately 5.5 years of age. After correcting for this level of under-reporting to the ACIR, MMR2 coverage for the entire cohort at five years of age was 52.9% (95% CI 52.3-53.4), and increased to 84.1% (95% CI 83.4-84.8) by approximately 5.5 years of age. This was 4.3% and 8.2%, respectively, higher than ACIR coverage estimates at the two ages. Based on the corrected MMR coverage estimates, 93% of the cohort was immune to measles due to vaccination. The most common parent-reported reason for incomplete vaccination was lack of knowledge about the MMR vaccination schedule. CONCLUSIONS: Measles elimination in Australia will require continued effort in vaccination coverage and timeliness among pre-school children. School-entry requirements are important for MMR2 uptake. Strategies are needed to improve reporting to the ACIR for more accurate measurement of coverage.