The Medicines Intelligence Data Platform: A Population-Based Data Resource From New South Wales, Australia.

BACKGROUND: The Medicines Intelligence (MedIntel) Data Platform is an anonymised linked data resource designed to generate real-world evidence on prescribed medicine use, effectiveness, safety, costs and cost-effectiveness in Australia. RESULTS: The platform comprises Medicare-eligible people who are ≥18 years and residing in New South Wales (NSW), Australia, any time during 2005-2020, with linked administrative data on dispensed prescription medicines (Pharmaceutical Benefits Scheme), health service use (Medicare Benefits Schedule), emergency department visits (NSW Emergency Department Data Collection), hospitalisations (NSW Admitted Patient Data Collection) plus death (National Death Index) and cancer registrations (NSW Cancer Registry). Data are currently available to 2022, with approval to update the cohort and data collections annually. The platform includes 7.4 million unique people across all years, covering 36.9% of the Australian adult population; the overall population increased from 4.8 M in 2005 to 6.0 M in 2020. As of 1 January 2019 (the last pre-pandemic year), the cohort had a mean age of 48.7 years (51.1% female), with most people (4.4 M, 74.7%) residing in a major city. In 2019, 4.4 M people (73.3%) were dispensed a medicine, 1.2 M (20.5%) were hospitalised, 5.3 M (89.4%) had a GP or specialist appointment, and 54 003 people died. Anti-infectives were the most prevalent medicines dispensed to the cohort in 2019 (43.1%), followed by nervous system (32.2%) and cardiovascular system medicines (30.2%). CONCLUSION: The MedIntel Data Platform creates opportunities for national and international research collaborations and enables us to address contemporary clinically- and policy-relevant research questions about quality use of medicines and health outcomes in Australia and globally.

COVID-19 Vaccine Uptake by Infection Status in New South Wales, Australia.

Using linked public health data from Australia to measure uptake of COVID-19 vaccination by infection status, we found coverage considerably lower among infected than uninfected persons for all ages. Increasing uptake of scheduled doses, including among previously infected persons after the recommended postinfection delay, is needed to reduce COVID-19 illness rates.

Regular high-frequency whole blood donation and risk of cardiovascular disease in middle-aged and older blood donors in Australia.

BACKGROUND: Previous mixed findings on the associations between whole blood (WB) donation and risk of cardiovascular diseases (CVD) may in part reflect inadequate adjustment for the "healthy donor effect" (HDE). METHODS: We used the Sax Institute's 45 and Up Study linked with blood donation history and other health-related databases to examine the association between regular, high-frequency WB donation and the risk of CVD. To mitigate the impact of HDE, we used a "5-years qualification period," in which donors must donate at least 1 WB donation in the 1st and 5th year of "qualification period." We then compared the risk of CVD in the years following the "qualification period" between the regular high-frequency WB donors (≥2 WB donation in each qualification year) and others using Cox proportional-hazards models. Analyses were adjusted for potential confounders, such as sociodemographic, lifestyle, and health-related variables, and results are reported separately for male and female donors. RESULTS: A total of 2736 male and 2917 female donors were included in the analyses. The median years of follow-up per donor was 5.84 years (Q1-Q3, 5.47-6.23). The rate of CVD hospitalization was 11.20 and 4.50 per 1000 person-years for males and females, respectively. In fully adjusted models, the risk (hazard ratio) of CVD in regular high-frequency donors compared to other donors was 0.93 (95% Confidence Interval (CI), 0.68-1.29) for males and 0.79 (95% CI, 0.49-1.28) for females. CONCLUSIONS: We did not observe a statistically significant reduction of CVD risk in regular, high-frequency WB donors when adjusted for potential confounders.

Associations between severe and notifiable respiratory infections during the first trimester of pregnancy and congenital anomalies at birth: a register-based cohort study.

BACKGROUND: Evidence regarding the association between acute respiratory infections during pregnancy and congenital anomalies in babies, is limited and conflicting. The aim of this study was to examine the association between acute respiratory infections during the first trimester of pregnancy and congenital anomalies in babies using record linkage. METHODS: We linked a perinatal register to hospitalisation and disease notifications in the Australian state of New South Wales (NSW) between 2001 to 2016. We quantified the risk of congenital anomalies, identified from the babies' linked hospital record in relation to notifiable respiratory and other infections during pregnancy using generalized Estimating Equations (GEE) adjusted for maternal sociodemographic and other characteristics. RESULTS: Of 1,453,037 birth records identified from the perinatal register between 2001 and 2016, 11,710 (0.81%) mothers were hospitalised for acute respiratory infection, 2850 (0.20%) had influenza and 1011 (0.07%) had high risk infections (a record of cytomegalovirus, rubella, herpes simplex, herpes zoster, toxoplasmosis, syphilis, chickenpox (varicella) and zika) during the pregnancy. During the first trimester, acute respiratory infection, influenza and high-risk infections were reported by 1547 (0.11%), 399 (0.03%) and 129 (0.01%) mothers. There were 15,644 (1.08%) babies reported with major congenital anomalies, 2242 (0.15%) with cleft lip/ plate, 7770 (0.53%) with all major cardiovascular anomalies and 1746 (0.12%) with selected major cardiovascular anomalies. The rate of selected major cardiovascular anomalies was significantly higher if the mother had an acute respiratory infection during the first trimester of pregnancy (AOR 3.64, 95% CI 1.73 to 7.66). The rates of all major congenital anomalies and all major cardiovascular anomalies were also higher if the mother had an acute respiratory infection during the first trimester of pregnancy, however the difference was no statistically significant. Influenza during the first trimester was not associated with major congenital anomalies, selected major cardiovascular anomalies or all major cardiovascular anomalies in this study. CONCLUSION: This large population-based study found severe acute respiratory infection in first trimester of pregnancy was associated with a higher risk of selected major cardiovascular anomalies in babies. These findings support measures to prevent acute respiratory infections in pregnant women including through vaccination.

Effectiveness of bivalent COVID-19 boosters against COVID-19 mortality in people aged 65 years and older, Australia, November 2022 to May 2023.

We followed 4,081,257 Australian adults aged ≥ 65 years between November 2022 and May 2023 for COVID-19-specific mortality, when recombinant SARS-CoV-2 Omicron lineages (predominantly XB and XBB) as well as BA.2.75 were circulating. Compared with a COVID-19 booster targeting ancestral SARS-CoV-2 given > 180 days earlier, the relative vaccine effectiveness against COVID-19 death of a bivalent (ancestral/BA.1 or ancestral/BA.4-5) booster given 8 to 90 days earlier was 66.0% (95%CI: 57.6 to 72.2%) and that of a monovalent ancestral booster given 8 to 90 days earlier was 44.7% (95%CI: 23.9 to 59.7%).

High Attack Rate of Severe Acute Respiratory Syndrome Coronavirus 2 B.1.1.529 Among 2-Dose Vaccinated Populations in 2 Indoor Entertainment Setting Outbreaks.

We estimated attack rates of severe acute respiratory syndrome coronavirus 2 Omicron (B.1.1.529) infection among people attending a nightclub and a graduation ball where >95% had at least 2 vaccine doses. Attack rates were 295 of 535 (55.1%) and 102 of 189 (54.0%), respectively (mean, 5 days postevent). At the ball, attack rates increased with time since vaccination: 12.5% among those vaccinated 1-2 months previously and 68.0% among those vaccinated ≥3 months previously; such differences were not found at the nightclub. Recent vaccination prevents Omicron infection, but is time and setting dependent, emphasizing the importance of nonpharmaceutical public health measures in addition to vaccine booster doses to maximize protection in high-risk contexts.

Hospitalisations for pelvic inflammatory disease in young Aboriginal women living in remote Australia: the role of chlamydia and gonorrhoea.

OBJECTIVE: Aboriginal women living in remote Australia experience a high burden of both chlamydia and gonorrhoea infections and disproportionately high rates of pelvic inflammatory disease (PID). We estimated for the first time the fraction of PID attributable to these infections in young Aboriginal women living in these settings. METHODS: Using published data from two large Australian studies (2002-2013; 2010-2014), we calculated the fraction of emergency department presentations and hospitalisations for PID attributable to chlamydia and/or gonorrhoea infection in Aboriginal women aged 16-29 years living in remote Australia. We used a Monte Carlo simulation to estimate the mean and 95% CIs for the assumed prevalence and population attributable fractions for PID for infection stratifications (chlamydia only, gonorrhoea only and dual infection) as well as for any infection (chlamydia and/or gonorrhoea). Additional outputs were calculated for chlamydia infection with/without gonorrhoea coinfection, and vice versa. RESULTS: The prevalence of chlamydia only was 12.9% (95% CI: 11.6% to 14.2%), gonorrhoea only was 7.8% (95% CI: 6.6% to 8.9%) and dual infection was 6.5% (95% CI: 5.8% to 7.2%); rate ratios of PID were 1.9 (95% CI: 1.5 to 2.3), 5.2 (95% CI: 4.3 to 6.4) and 4.6 (95% CI: 3.8 to 5.5), respectively. The overall fraction of PID attributable to chlamydia and/or gonorrhoea was 40.2% (95% CI: 36.0% to 44.4%); any gonorrhoea was 33.4% (95% CI: 29.2% to 37.8%) and any chlamydia was 20.6% (95% CI: 16.9% to 24.6%). CONCLUSION: Our study demonstrates the importance of calculating the fraction of PID related to chlamydia and gonorrhoea in the local context, demonstrating the major contribution gonorrhoea makes to PID hospitalisations among Australian Aboriginal women living in remote settings. To significantly and sustainably reduce the unacceptable rate of PID in this population, strategies are urgently needed to improve timely testing and treatment and recognition and management of PID in primary care.

Impact of a structured older persons health assessment on herpes zoster vaccine uptake in Australian primary care.

Vaccine uptake in adult immunisation programs is often suboptimal. We aimed to assess the impact of the structured older persons health assessment (health assessment) on herpes zoster (zoster) vaccine uptake in Australia. We used national general practice electronic medical records (MedicineInsight) of encounters with patients aged 75-79 years because these patients were age-eligible for both free zoster vaccines and health assessments in the two years following the addition of zoster vaccine to the national immunisation program (Nov 2016-Dec 2018). Due to repeated encounters, we used generalized estimating equations with each patient treated as a clustering variable to analyse the comparison of rates of zoster vaccine administration during encounters where a health assessment was provided versus encounters where the health assessment was not provided. In analyses there were 31,876 patients with a total of 266,204 eligible general practice encounters. Of the 5018 encounters where a health assessment was provided, 592 zoster vaccinations also occurred on the same day (118.0/1000 encounters); for the 261,186 encounters where no health assessment was provided, 9226 zoster vaccinations occurred (35.3/1000 encounters). Zoster vaccine was more likely to be administered during a general practice encounter with a health assessment compared to encounters without one (adjusted odds ratio 2.99; 95% CI: 2.76-3.23). In conclusion, the structured older persons health assessment, which acts as both an incentive and a reminder for healthcare providers to recommend vaccinations in adults improves uptake of zoster vaccine in eligible adults. Such interventions may have a role in improving vaccine uptake among older adults.

Characteristics Associated with Monitoring and Treatment of Chronic Hepatitis B in a Large Cohort of Australian Adults.

BACKGROUND: Regular monitoring and treatment of chronic hepatitis B (CHB) are known to reduce the risk of hepatocellular carcinoma. We sought to describe patterns of monitoring and treatment among adults diagnosed with CHB in Australia. METHODS: Population-based prospective cohort study of Australian adults aged 45 + years followed by record-linkage to hepatitis B notifications, monitoring and treatment. Proportions of those with CHB who: had viral load test; were dispensed antiviral treatment; and had ultrasound surveillance were estimated. The characteristics associated with viral load test and ultrasound surveillance were examined using logistic regression. RESULTS: A total of 576 adults with CHB were identified. From 2008 to 2015, 14.8% (85/576) had at least one viral load test recorded every 2 years and 19.1% (110/576) had at least one antiviral treatment recorded, 19.9% (58/292) had at least one ultrasound recorded every year among those eligible for ultrasound surveillance. A record of having at least one viral load test every 2 years was more likely among adults born in Asia compared to Australian-born (21.4% vs 8.6%), those notified in more recent years compared to earlier years, and those on antiviral treatment compared to not on treatment. Increasing proportions of cases had records of at least one viral load test over time (2008: 10.5%, 2015: 27.2%) and at least one antiviral treatment (2008: 3.0%, 2015: 18.5%). CONCLUSIONS: In Australian adults, estimates of care interventions for CHB management have increased over time but still fall short of targets recommended in the National Hepatitis B Strategy.

Identifying gaps in dual protection from sexually transmissible infections and unintended pregnancies among Australian women: an observational study.

Background Dual protection refers to the simultaneous prevention of sexually transmissible infection (STI) and unintended pregnancies. Optimal contraception and STI prevention strategies sometimes fail to align. Methods Using data from a large nationally representative population-based survey, we analysed the contraception and STI prevention behaviours at the last vaginal intercourse among 2420 heterosexually active women aged 16-34years who had participated in the Second Australian Study of Health and Relationships, 2012-13. Results At their last vaginal intercourse, most women (95%) used contraception and half (49%) used condoms, either as a sole multipurpose method or in conjunction with another type of contraception. Condom use was highest (72%) among women whose most recent partner was a casual or occasional partner, followed by women with a regular partner (59%) and women with a cohabiting regular partner (40%). One-third of the women (34%) used condoms as a sole method, and 14% used oral contraceptives together with a condom. Few women used implants or intrauterine devices (8%) and, among them, very few women also used condoms (<1%). Among the women who used a condom at their last vaginal intercourse, 49% reported both the correct use for STI prevention and consistent condom use during the previous 6months. Among women using condoms, correct and consistent use was also highest among women whose most recent partner was a casual or occasional partner (76%). Conclusions Although almost all women used contraception and half used dual protection, few benefited from the protective effects of using condoms together with highly effective contraception.

Practice- and individual-level antibiotic prescribing associated with antibiotic treatment non-response in respiratory tract infections: a national retrospective observational study.

OBJECTIVES: Antibiotic overuse results in adverse clinical outcomes. This study quantified the independent contributions of practice- and individual patient-level antibiotic prescribing to antibiotic treatment non-response in respiratory tract infections (RTIs) in primary care. METHODS: RTI episodes with antibiotic prescribed in 2018 were extracted from an Australian national general practice database. Practices were classified into tertiles by total antibiotic prescriptions per patient and ratios of broad- to narrow-spectrum antibiotic prescriptions. The association between practice- and individual patient-level antibiotic prescribing in the previous year and antibiotic treatment non-response (defined as prescription of a different antibiotic) ≤30 days after the initial RTI episode was quantified using generalized estimating equations. RESULTS: Of 84 597 RTI episodes with antibiotics prescribed in 558 practices, 5570 (6.6%) episodes of treatment non-response were identified. Patients with high individual-level antibiotic prescribing (≥4 prescriptions/year) had an increased risk of treatment non-response (versus no prescriptions/year: OR = 1.64, 95% CI = 1.52-1.77). At the practice level, there was no significant association between total antibiotic prescriptions per patient and treatment non-response (high versus low: OR = 0.99, 95% CI = 0.92-1.06). RTI episodes in practices with high broad- to narrow-spectrum antibiotic ratios had an increased risk of treatment non-response (versus low-ratio practices: OR = 1.14, 95% CI = 1.05-1.23); this association was only observed among patients with <4 antibiotic prescriptions/year. CONCLUSIONS: The general practice-level broad- to narrow-spectrum antibiotic ratio was a predictor of RTI antibiotic treatment non-response in patients with lower individual-level antibiotic use. The measure of practice-level antibiotic prescribing could potentially guide the improvement of antibiotic treatment.

Use of disease-modifying antirheumatic drugs and the subsequent risk of herpes zoster in older adults.

OBJECTIVES: To examine the association between DMARD use and subsequent risk of herpes zoster in a large, heterogeneous and prospective population-based cohort. METHODS: Using data from a cohort of adults (45 and Up Study) recruited between 2006 and 2009 and linked to pharmaceutical, hospital and death data (2004-2015), the effect of DMARD use on zoster risk was analysed using Cox proportional hazards models, adjusting for sociodemographic characteristics, comorbidities and corticosteroid use. RESULTS: Among 254 065 eligible participants, over 1 826 311 person-years follow-up, there were 6295 new DMARD users and 17 024 incident herpes zoster events. Compared with non-users, the risk of zoster was higher in those who used biologic (b)DMARDs, either alone or in combination with conventional synthetic (cs)DMARDs than in those who only used csDMARDs (adjusted hazard ratio [aHR] 2.53 [95% CI: 2.03, 3.16]) for bDMARDs vs 1.48 [95% CI: 1.33, 1.66] for csDMARDs, P-heterogeneity < 0.001; reference: non-users). Among users of csDMARDs, compared with non-users, zoster risks were highest in those using exclusively cyclophosphamide (aHR 2.69 [95% CI: 1.89, 3.83]), more moderate in those using azathioprine (aHR 1.57 [95% CI: 1.07, 2.30]) and hydroxychloroquine (aHR 1.43 [95%CI: 1.11, 1.83]) and not elevated in users of methotrexate (aHR 1.24 [95% CI: 0.98, 1.57]), sulfasalazine (aHR 1.00 [95% CI: 0.71, 1.42]) and leflunomide (aHR 0.41 [95% CI: 0.06, 2.88]). CONCLUSIONS: The risk of zoster was high among bDMARD and cyclophosphamide users. Also, the risk was increased in those using hydroxychloroquine alone and in combination with methotrexate but not methotrexate alone. Preventative strategies such as zoster vaccination or antiviral therapies should be considered in these populations if not contraindicated.

Visits to general practitioners after iron-related deferrals from blood donation in middle-aged and older Australian blood donors.

BACKGROUND: Australian Red Cross Lifeblood (Lifeblood) advises donors to visit their general practitioner (GP) for medical follow-up if they are deferred from donating due to having a lower than acceptable level of hemoglobin (Hb) and/or serum ferritin (iron-related deferrals). METHODS: We used the Sax Institute's 45 and Up Study data linked to Lifeblood's donor datasets and other health administrative datasets. We examined the rate of visits to a GP after iron-related deferral from donation, and investigated whether an early visit to a GP (within 30 days following the deferral) had an impact on return to make successful donation within 12, 18, and 24 months compared to a delayed or no GP visit. RESULTS: A total of 1928 donors underwent iron-related deferral. The rate of visits to a GP in the first month after deferral was double the rate observed a month prior. However, only 52.4% of those deferred visited a GP early with slightly more than half of those receiving an iron-monitoring test. Return to donate over the 24 months was lower in donors visiting their GP early (adjusted Hazard Ratio [aHR] 0.86, 95% CI 0.77-0.97). Early GP visitors were likely to have a relatively poorer health than the delayed or no GP visit group. CONCLUSIONS: Only half of the donors with an iron-related deferral followed advice from Lifeblood and visited their GP within 30 days of deferral, and these donors have a significantly reduced likelihood of future successful blood donation which may be due to their relatively poorer health status.

Willingness of blood donors in Australia to provide additional data and blood sample for health research.

BACKGROUND: Many blood collection agencies are generating important data on donor health outcomes using large-scale blood donor cohort studies. Such studies can be very effective when donors provide access to linkage of their data to external health databases, and storage and genomic testing of their blood sample. In this study, we aimed to assess the willingness of Australian blood donors to provide additional data and blood sample for donation-related and other health research. STUDY DESIGN AND METHODS: We invited 2017 donors to complete a survey using four methods (postal letter, postal letter and email, email only, and in-center recruitment). The survey asked for information on demographics, lifestyle behaviors, health, experience and attitude to blood donation, and willingness to give blood sample and additional data for research. RESULTS: Response rates ranged from 23.8% for email only to 77.2% for in-center recruitment. Of those who responded (n = 827), 95.5% indicated they would be willing to provide a blood sample for donation and transfusion-related research. Of these, >90.0% were willing for their sample to be used in research involving genetic testing and other health-related topics. Also, >90.0% were willing to consent for linkage of their information to external health databases. CONCLUSIONS: Donors surveyed reported a high willingness to participate in health research by completing surveys, allowing linkage to external datasets, and providing a blood sample. These findings provide strong support for future longitudinal research studies with Australian blood donors.

Microbiology testing and antibiotic treatment for urinary tract infections in general practice: a nationwide observational study.

PURPOSE: Routine urine testing is recommended prior to antibiotic treatment for urinary tract infections (UTIs) among high-risk groups for complicated UTIs. This study aims to examine whether the proportion of UTI encounters where antibiotics are prescribed that have accompanying urine testing differs by patient groups. METHODS: A retrospective analysis was conducted using records of general practice encounters for UTIs occurring between January 2013 and July 2018 in an Australian national database. We calculated the proportion of UTI encounters with antibiotics prescribed that had accompanying urine microbiology testing and the odds ratios for the likelihood of testing by patient groups using generalised estimating equations. RESULTS: Of 132,688 UTI encounters with antibiotics prescribed, 95,800 (72.2%) were accompanied by urine testing. Among high-risk groups for complicated UTIs and expected to have a high likelihood of testing, we found pregnant women [82.6% vs. non-pregnant 72.3%, adjusted odds ratio (aOR) 1.82, 95% confidence intervals (CI) 1.55-2.12] and children aged 5-9 years (77.6% vs. 20-44 years 72.0%, aOR 1.33, 95% CI 1.22-1.45) had relatively high odds of testing. However, children aged < 5 years (68.7% vs. 20-44 years 72.0%, aOR 0.83, 95% CI 0.76-0.90), patients with recurrent UTIs (69.0% compared to first-onset UTIs 73.6%, aOR 0.81, 95% CI 0.79-0.83), and patients in residential aged care facilities (67.3% vs. not 72.3%, aOR 0.80, 95% CI 0.72-0.90) had relatively low odds of testing. CONCLUSION: Our results suggest inconsistencies and potential underuse of urine testing when antibiotics were prescribed for high-risk groups in UTI management. Further antibiotic stewardship is needed to improve guideline-based antibiotic prescribing for UTIs.

High risk groups for severe COVID-19 in a whole of population cohort in Australia.

BACKGROUND: Increasing age is the strongest known risk factor for severe COVID-19 disease but information on other factors is more limited. METHODS: All cases of COVID-19 diagnosed from January-October 2020 in New South Wales Australia were followed for COVID-19-related hospitalisations, intensive care unit (ICU) admissions and deaths through record linkage. Adjusted hazard ratios (aHR) for severe COVID-19 disease, measured by hospitalisation or death, or very severe COVID-19, measured by ICU admission or death according to age, sex, socioeconomic status and co-morbidities were estimated. RESULTS: Of 4054 confirmed cases, 468 (11.5%) were classified as having severe COVID-19 and 190 (4.7%) as having very severe disease. After adjusting for sex, socioeconomic status and comorbidities, increasing age led to the greatest risk of very severe disease. Compared to those 30-39 years, the aHR for ICU or death from COVID-19 was 4.45 in those 70-79 years; 8.43 in those 80-89 years; 16.19 in those 90+ years. After age, relative risks for very severe disease associated with other factors were more moderate: males vs females aHR 1.40 (95%CI 1.04-1.88); immunosuppressive conditions vs none aHR 2.20 (1.35-3.57); diabetes vs none aHR 1.88 (1.33-2.67); chronic lung disease vs none aHR 1.68 (1.18-2.38); obesity vs not obese aHR 1.52 (1.05-2.21). More comorbidities was associated with significantly greater risk; comparing those with 3+ comorbidities to those with none, aHR 5.34 (3.15-9.04). CONCLUSIONS: In a setting with high COVID-19 case ascertainment and almost complete case follow-up, we found the risk of very severe disease varies by age, sex and presence of comorbidities. This variation should be considered in targeting prevention strategies.

Risk of recurrent herpes zoster in a population-based cohort study of older adults.

BACKGROUND: There are limited data on zoster recurrence. OBJECTIVE: To examine in detail zoster recurrence in a population-based cohort. METHODS: Using data from a large cohort (The 45 and Up Study) with linked medical data (2004-2015), the incidences of first and recurrent zoster were examined by using survival analysis methods. RESULTS: Over 1,846,572 person-years of follow-up, of 17,413 participants who had a first zoster episode (incidence, 9.43 per 1000 person-years; 95% confidence interval, 9.29-9.57), 675 (3.9%) experienced a recurrence. The mean time between first and recurrent zoster was 2 years for those aged 45-54 years and 3 years for those aged 55 years and older. Among those with a first zoster, the incidence of recurrence was 11.05 (95% confidence interval, 10.24-11.91) per 1000 person-years, and higher recurrence incidence occurred in women compared to men, in younger compared to older participants, and in immunosuppressed compared to nonimmunosuppressed participants. Recurrence appeared lower in the 12 months after zoster onset but then remained consistent at approximately 12.00 per 1000 person-years in the following 8 years. LIMITATIONS: Recurrence may be underestimated because of the use of administrative data for case ascertainment. Potential misclassification of nonimmunosuppressed participants. CONCLUSIONS: Our results support the vaccination of people who have already experienced zoster and underpin the need for additional studies on immunogenicity and vaccine efficacy in these populations.

Effectiveness of Acellular Pertussis Vaccine in Older Adults: Nested Matched Case-control Study.

BACKGROUND: Despite recommendations that older adults receive acellular pertussis vaccines, data on direct effectiveness in adults aged over 50 years are sparse. METHODS: A case-control study nested within an adult cohort. Cases were identified from linked pertussis notifications and each matched to 3 controls on age, sex, and cohort recruitment date. Cases and controls were invited to complete a questionnaire, with verification of vaccination status by their primary care provider. Vaccine effectiveness (VE) was estimated by conditional logistic regression, with adjustment for reported contact with children and area of residence. RESULTS: Of 1112 notified cases in the cohort, we had complete data for 333 cases and 506 controls. Among 172 PCR-diagnosed cases (mean age, 61 years), 11.2% versus 19.5% of controls had provider-verified pertussis vaccination, on average, 3.2 years earlier. Adjusted VE against PCR-diagnosed pertussis was 52% (95% CI, 15-73%), nonsignificantly higher if vaccinated within 2 years (63%; -5-87%). Adjusted VE was similar in adults born before 1950, presumed primed by natural infection (51%; -8-77%) versus those born 1950 or later who may have received whole-cell pertussis vaccine (53%; -11-80%) (P-heterogeneity = 0.9). Among 156 cases identified by single-point serology, adjusted VE was -55% (-177-13%). CONCLUSIONS: We found modest protection against PCR-confirmed pertussis among older adults (mean age, 61 years; range, 46-81 years) within 5 years after acellular vaccine. The most likely explanation for the markedly divergent VE estimate from cases identified by single-titer serology is misclassification arising from limited diagnostic specificity in our setting.

Trends in chronic hepatitis B prevalence in Australian women by country of birth, 2000 to 2016.

Routine antenatal screening for chronic hepatitis B (HBV) in countries with high migrant populations provides an opportunity to monitor trends in HBV prevalence and can inform estimates locally and in countries with limited seroprevalence data. We linked perinatal birth register records with HBV notifications in the largest Australian state, over the period 2000-2016. Among women aged 15-44 years, we estimated age-standardized chronic HBV prevalence overall and by country of birth and also estimated trends in age-standardized HBV prevalence over time using regression modelling. Among 903 831 women, 8001 linked to a chronic HBV infection record (overall age-standardized prevalence 0.76%, 95% CI: 0.74-0.78). Prevalence varied by country of birth with the highest estimates among women born in Sierra Leone (11.13%, 95% CI: 8.29-13.96), Taiwan (8.08%, 95% CI: 6.74%-9.43%), Cambodia (7.47%, 95% CI: 6.50%-8.45%) and Vietnam (7.36%, 95% CI: 6.97%-7.75%); more moderate estimates among women from North Korea (2.76%, 95% CI: 1.99-3.53) and Samoa (2.64%, 95% CI: 1.99%-3.29%); prevalence was 0.18% (95% CI: 0.17-0.19) in Australian-born women. Over 17 years, there were significant reductions in HBV prevalence among all women (from 0.88% in 2000 to 0.57% in 2016; P < .0001). Among women from high prevalence countries, the greatest absolute reductions were observed among those from Taiwan (10.1%, P < .001) followed by Tonga (5.4%, P < .001), whereas no reductions were observed for women born in Vietnam (P = .08), South Korea (P = .41) and Sudan (P = .06). In conclusion, routine antenatal HBV testing can be used to inform HBV prevalence estimates and vaccine programme impact in countries with limited surveillance and high migration to Australia.

Microbiology testing associated with antibiotic dispensing in older community-dwelling adults.

BACKGROUND: It is commonly recommended that microbiological assessment should accompany the use of antibiotics prone to resistance. We sought to estimate the rate of microbiology testing and compare this to dispensing of the World Health Organization classified "watch" group antibiotics in primary care. METHODS: Data from a cohort of older adults (mean age 69 years) were linked to Australian national health insurance (Pharmaceutical Benefits Scheme & Medicare Benefits Schedule) records of community-based antibiotic dispensing and microbiology testing in 2015. Participant characteristics associated with greater watch group antibiotic dispensing and microbiology testing were estimated using adjusted incidence rate ratios (aIRR) and 95% confidence intervals (CI) in multivariable zero-inflated negative binomial regression models. RESULTS: In 2015, among 244,299 participants, there were 63,306 watch group antibiotic prescriptions dispensed and 149,182 microbiology tests conducted; the incidence rate was 0.26 per person-year for watch group antibiotic dispensing and 0.62 for microbiology testing. Of those antibiotic prescriptions, only 19% were accompanied by microbiology testing within - 14 to + 7 days. After adjusting for socio-demographic factors and co-morbidities, individuals with chronic respiratory diseases were more likely to receive watch group antibiotics than those without, e.g. asthma (aIRR:1.59, 95%CI:1.52-1.66) and chronic obstructive pulmonary disease (COPD) (aIRR:2.71, 95%CI:2.48-2.95). However, the rate of microbiology testing was not comparably higher among them (with asthma aIRR:1.03, 95%CI:1.00-1.05; with COPD aIRR:1.00, 95%CI:0.94-1.06). CONCLUSIONS: Priority antibiotics with high resistance risk are commonly dispensed among community-dwelling older adults. The discord between the rate of microbiology testing and antibiotic dispensing in adults with chronic respiratory diseases suggests the potential for excessive empirical prescribing.