Confidence intervals for weighted proportions

Visual acuity and causes of central visual loss in the adult Danish population 2020-2022. Results from the FORSYN study

PURPOSE

Knowledge of visual health in the population is necessary for designing and implementing measures to handle visual handicap. The purpose of the FORSYN (Forekomst af synshandicap og synshjaelpemidler i Danmark) project was to study visual health in the Danish population 2020-2022 after implementation of the recent advances in the management of choroidal and retinal vascular disease. The present study reports visual acuity and causes of central visual loss from this study.

METHODS

A population-representative sample of 10 350 citizens living within 40 kilometres from Aarhus University Hospital were invited to answer a questionnaire about quality of life related to vision, measurement of visual acuity and a non-mydriatic examination of the eyes. The data were corrected for selection bias on the basis of demographic and socioeconomic factors so that the results could be projected to represent the adult Danish population.

RESULTS

Population-adjusted visual acuity in ETDRS letters (mean ± SD) differed significantly (p < 0.0001) among the worse eye (84.1 ± 0.25), the better eye (88.4 ± 0.11) and binocularly (89.2 ± 0.15). Social blindness affected 0.22% (95% CI: 0.14%-0.33%) of the population and was in none of the studied persons due to exudative age-related macular degeneration (AMD) or diabetic retinopathy. The most frequent causes of visual loss were atrophic AMD, neuro-ophthalmic disorders and other chorioretinal diseases.

CONCLUSIONS

Recent advances in the therapy of chorioretinal vascular diseases have been paralleled with a reduction in central vision loss secondary to exudative AMD and diabetic retinopathy in Denmark. The demographic development can be expected to increase the demand for treatments of vision-threatening diseases that mainly affect older persons.

Incidence of Lyme neuroborreliosis in Denmark: Exploring observed trends using public surveillance data, 2015-2019

Lyme neuroborreliosis (LNB) can be a serious manifestation of Lyme borreliosis. We describe the incidence, time trends and geographic distribution of LNB in Denmark. We obtained LNB cases reported by laboratories and physicians (2015-2019) from the online platform maintained by the Statens Serum Institut (SSI) (2021b). The LNB incidence (per 100,000 persons) was calculated by dividing LNB cases by the population data (denominator) obtained from Statistics Denmark (2021). Between 2015 and 2019, laboratories reported annually 162 to 200 LNB cases, while physicians reported 48 to 68 cases. The annual LNB incidence notified by laboratories ranged from 2.8 (95% CI: 2.4‒3.3) to 3.4 (95% CI: 3.0‒4.0) per 100,000 persons for the 5 study years. The average annual LNB incidence per 100,000 persons for 5 Danish regions ranged from 2.3 to 3.3; for 11 provinces, from 1.9 to 7.6; and for 98 municipalities, from 0 to 22.1. Incidence peaks occurred in persons 5‒14 and 65‒74 years of age. Higher incidences were observed among males versus females in all age groups. LNB cases were reported throughout the year, with peaks in July to September. Notified LNB incidence in Denmark was moderate with no evidence of decline. Cases occurred across all regions but were focally concentrated among residents of some municipalities. Expanding the current surveillance system to include other manifestations of LB would be valuable to better understand geographic endemicity to inform targeted preventive measures.

German federal-state-wide seroprevalence study of 1st SARS-CoV-2 pandemic wave shows importance of long-term antibody test performance

Background

Reliable data on the adult SARS-CoV-2 infection fatality rate in Germany are still scarce. We performed a federal state-wide cross-sectional seroprevalence study named SaarCoPS, that is representative for the adult population including elderly individuals and nursing home residents in the Saarland.

Methods

Serum was collected from 2940 adults via stationary or mobile teams during the 1^st pandemic wave steady state period. We selected an antibody test system with maximal specificity, also excluding seroreversion effects due to a high longitudinal test performance. For the calculations of infection and fatality rates, we accounted for the delays of seroconversion and death after infection.

Results

Using a highly specific total antibody test detecting anti-SARS-CoV-2 responses over more than 180 days, we estimate an adult infection rate of 1.02% (95% CI: [0.64; 1.44]), an underreporting rate of 2.68-fold (95% CI: [1.68; 3.79]) and infection fatality rates of 2.09% (95% CI: (1.48; 3.32]) or 0.36% (95% CI: [0.25; 0.59]) in all adults including elderly individuals, or adults younger than 70 years, respectively.

Conclusion

The study highlights the importance of study design and test performance for seroprevalence studies, particularly when seroprevalences are low. Our results provide a valuable baseline for evaluation of future pandemic dynamics and impact of public health measures on virus spread and human health in comparison to neighbouring countries such as Luxembourg or France.

Longitudinal SARS-CoV-2 seroprevalence in Portugal and antibody maintenance 12 months after infection

During the COVID-19 pandemic, Portugal has experienced three distinct SARS-CoV-2 infection waves. We previously documented the prevalence of SARS-CoV-2 immunity, measured by specific antibodies, in September 2020, 6 months after the initial moderate wave. Here, we show the seroprevalence changes 6 months later, up to the second week of March 2021, shortly following the third wave, which was one of the most severe in the world, and 2 months following the start of the vaccination campaign. A longitudinal epidemiological study was conducted, with a stratified quota sample of the Portuguese population. Serological testing was performed, including ELISA determination of antibody class and titers. The proportion of seropositives, which was 2.2% in September 2020, rose sharply to 17.3% (95% CI: 15.8-18.8%) in March 2021. Importantly, circulating IgG and IgA antibody levels were very stable 6 months after the initial determination and up to a year after initial infection, indicating long-lasting infection immunity against SARS-CoV-2. Moreover, vaccinated people had higher IgG levels from 3 weeks post-vaccination when compared with previously infected people at the same time post-infection.

Adenoma and Serrated Lesion Detection by Colonoscopy Indication: The ADR-ESS (ADR Extended to all Screening/Surveillance) Score

BACKGROUND

The adenoma detection rate at screening (ADR) predicts interval colorectal cancer. Monitoring other lesion detection rates and colonoscopy indications has been proposed. We developed a comprehensive, automated colonoscopy audit program based on standardized clinical documentation, explored detection rates across indications, and developed the Adenoma Detection Rate - Extended to all Screening / Surveillance (ADR-ESS) score.

METHODS

In a prospective cohort study, we calculated overall and advanced adenoma and sessile serrated lesion (SSL) detection rates among 15,253 colonoscopies by 35 endoscopists from 4 endoscopy units across all colonoscopy indications. We explored correlations between detection rates, and the precision and stability of ADR-ESS versus ADR.

RESULTS

The overall "screening, first" ADR was 36.3% (95% confidence interval [CI], 34.5%-38.1%). The adenoma detection rate was lower for "screening, not first" (relative rate [RR], 0.80; 95% CI, 0.74-0.87) and "family history" (RR, 0.84; 95% CI, 0.74-0.96), and higher for "surveillance" (RR, 1.22; 95% CI, 1.15-1.31) and "follow-up, FIT" (RR, 1.21; 95% CI, 1.07-1.37). For "screening, first," the detection rates for advanced adenoma, SSL, and advanced SSL were 6.7% (95% CI, 5.7%-7.7%), 7.2% (95% CI, 6.2%-8.2%), and 2.6% (95% CI, 2.0%-3.2%), respectively. Adenoma and SSL detection were correlated (r = 0.44; P = .008). ADR-ESS had substantially narrower confidence intervals and less period-to-period variability than ADR, and was not improved by weighting for indication volume and correction for detection by indication.

CONCLUSIONS

Comprehensive, automated colonoscopy audit based on standardized clinical documentation is feasible. Adenoma detection is a fair but imperfect proxy for SSL detection. ADR-ESS increases the precision of adenoma detection assessments and emphasizes quality across colonoscopy indications.

Impact of National Containment Measures on Decelerating the Increase in Daily New Cases of COVID-19 in 54 Countries and 4 Epicenters of the Pandemic: Comparative Observational Study

BACKGROUND

Coronavirus disease (COVID-19) is a worldwide epidemic, and various countries have responded with different containment measures to reduce disease transmission, including stay-at-home orders, curfews, and lockdowns. Comparative studies have not yet been conducted to investigate the impact of these containment measures; these studies are needed to facilitate public health policy-making across countries.

OBJECTIVE

The aim of this study was to describe and evaluate the impact of national containment measures and policies (stay-at-home orders, curfews, and lockdowns) on decelerating the increase in daily new cases of COVID-19 in 54 countries and 4 epicenters of the pandemic in different jurisdictions worldwide.

METHODS

We reviewed the effective dates of the national containment measures (stay-at-home order, curfew, or lockdown) of 54 countries and 4 epicenters of the COVID-19 pandemic (Wuhan, New York State, Lombardy, and Madrid), and we searched cumulative numbers of confirmed COVID-19 cases and daily new cases provided by health authorities. Data were drawn from an open, crowdsourced, daily-updated COVID-19 data set provided by Our World in Data. We examined the trends in the percent increase in daily new cases from 7 days before to 30 days after the dates on which containment measures went into effect by continent, World Bank income classification, type of containment measures, effective date of containment measures, and number of confirmed cases on the effective date of the containment measures.

RESULTS

We included 122,366 patients with confirmed COVID-19 infection from 54 countries and 24,071 patients from 4 epicenters on the effective dates on which stay-at-home orders, curfews, or lockdowns were implemented between January 23 and April 11, 2020. Stay-at-home, curfew, and lockdown measures commonly commenced in countries with approximately 30%, 20%, or 10% increases in daily new cases. All three measures were found to lower the percent increase in daily new cases to <5 within one month. Among the countries studied, 20% had an average percent increase in daily new cases of 30-49 over the seven days prior to the commencement of containment measures; the percent increase in daily new cases in these countries was curbed to 10 and 5 a maximum of 15 days and 23 days after the implementation of containment measures, respectively.

CONCLUSIONS

Different national containment measures were associated with a decrease in daily new cases of confirmed COVID-19 infection. Stay-at-home orders, curfews, and lockdowns curbed the percent increase in daily new cases to <5 within a month. Resurgence in cases within one month was observed in some South American countries.

Controversy and debate on dengue vaccine series-paper 1: review of a licensed dengue vaccine: inappropriate subgroup analyses and selective reporting may cause harm in mass vaccination programs

Severe life-threatening dengue fever usually occurs when a child is infected by dengue virus a second time. This is caused by a phenomenon called antibody-dependent enhancement (ADE). Since dengue vaccines can mimic a first infection in seronegative children (those with no previous infection), a natural infection later in life could lead to severe disease. The possibility that dengue vaccines can cause severe dengue through ADE has led to serious concern regarding the safety of mass vaccination programs. A published meta-analysis addressed this safety issue for a new vaccine against dengue fever-Dengvaxia. The trials in this meta-analysis have been used to campaign for mass vaccination programs in developing countries. We discuss the results of this paper and point out problems in the analyses. Reporting the findings in an Asian trial (CYD14), the authors show a sevenfold rise in one outcome-hospitalization for dengue fever in children <5 years old. However, they fail to point out two signals of harm for another outcome-hospitalization for severe dengue fever (as confirmed by an independent data monitoring committee): 1. In children younger than 9 years, the relative risk was 8.5 (95% confidence interval [CI]: 0.5, 146.8), and 2. In the overall study group, the relative risk was 5.5 (95% CI: 0.9, 33). The authors conduct a subgroup analysis to support claims that the vaccine is probably safe among children aged 9 years or more. This subgroup analysis has limited credibility because: (1) it was a post hoc analysis; (2) it was one of a large number of subgroup analyses; (3) the test of interaction was not reported, but was insignificant (P = 0.14); and (4) there is no biological basis for a threshold age of 9 years. The more likely explanation for the higher risk in younger children is ADE, that is, more frequent seronegativity, rather than age itself. The selective reporting and inappropriate subgroup claims mask the potential harm of dengue mass vaccination programs. Countries planning public use of the vaccine must conduct diligent postmarketing surveillance, secure informed consent from parents of potential recipients, and closely monitor the results of ongoing long-term follow-up of clinical trial participants.

Use of assisted reproductive technology treatment as reported by mothers in comparison with registry data: the Upstate KIDS Study

OBJECTIVE

To assess the validity of maternally reported assisted reproductive technologies (ART) use and to identify predictors of reporting errors.

DESIGN

Linkage study.

SETTING

Not applicable.

PATIENT(S)

A total of 5,034 (27%) mothers enrolled, from whom 4,886 (97%) self-reported information about use of infertility treatment, including ART, for the index birth.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Four measures of validity (sensitivity, specificity, positive and negative predictive values) and use of net reclassification improvement (NRI) methods to identify predictors associated with concordant/discordant maternal reporting.

RESULT(S)

The Upstate New York Infant Development Screening Program (Update KIDS Study) was linked with the Society for Assisted Reproductive Technology Clinic Outcome Reporting System (SART CORS) using a defined algorithm for 2008-2010. The sensitivity, specificity, positive and negative predictive values were high (0.93, 0.99, 0.80, and 1.00, respectively). The validity of maternal report was high, reflecting few differences by participant characteristics except for maternal age dichotomized at 29 years as identified with NRI methods.

CONCLUSION(S)

Maternally reported ART is valid, with little variation across various characteristics. No strong predictors of discordant reporting were found, supporting the utility of population-based research with SART CORS linkage.

Estimating the agreement and diagnostic accuracy of two diagnostic tests when one test is conducted on only a subsample of specimens

We focus on the efficient usage of specimen repositories for the evaluation of new diagnostic tests and for comparing new tests with existing tests. Typically, all pre-existing diagnostic tests will already have been conducted on all specimens. However, we propose retesting only a judicious subsample of the specimens by the new diagnostic test. Subsampling minimizes study costs and specimen consumption, yet estimates of agreement or diagnostic accuracy potentially retain adequate statistical efficiency. We introduce methods to estimate agreement statistics and conduct symmetry tests when the second test is conducted on only a subsample and no gold standard exists. The methods treat the subsample as a stratified two-phase sample and use inverse-probability weighting. Strata can be any information available on all specimens and can be used to oversample the most informative specimens. The verification bias framework applies if the test conducted on only the subsample is a gold standard. We also present inverse-probability-weighting-based estimators of diagnostic accuracy that take advantage of stratification. We present three examples demonstrating that adequate statistical efficiency can be achieved under subsampling while greatly reducing the number of specimens requiring retesting. Naively using standard estimators that ignore subsampling can lead to drastically misleading estimates. Through simulation, we assess the finite-sample properties of our estimators and consider other possible sampling designs for our examples that could have further improved statistical efficiency. To help promote subsampling designs, our R package CompareTests computes all of our agreement and diagnostic accuracy statistics.

Transmission of pandemic influenza A (H1N1) 2009 within households: Edmonton, Canada

BACKGROUND

In April 2009, a novel influenza A, subtype H1N1, now referred to as the Pandemic (H1N1) 2009 virus (pH1N1), began circulating in countries around the world. Describing the transmission characteristics of this novel influenza A virus is important to predict current, and future, disease spread. The Public Health response to the first wave of pH1N1 in Alberta focused on the identification and management of secondary cases within households.

OBJECTIVES

The purpose of this study was to describe transmission characteristics of pH1N1 in households in Edmonton, the capital city of Alberta, during the first wave, and to identify the serial interval and secondary attack rate (SAR) in this setting.

STUDY DESIGN

This is a prospective analysis of pH1N1 household transmission within 87 urban Canadian households between April 30 and June 9, 2009; with each household having at least one laboratory-confirmed case. The secondary attack rate was calculated in the 262 household contacts using a weighted average by number of susceptible individuals in each household. The serial interval, or time to illness in secondary cases, was analyzed using survival analysis with a Weibull model.

RESULTS

Within the 87 households, 42 (48.3%) had no secondary cases develop; 25 (28.7%) had one secondary case develop; and 20 (22.9%) had more than one secondary case develop. The secondary attack rate did not decrease with increasing household size and households with two members exhibited the lowest secondary attack rate at 14.1%. Children under the age of 19, and individuals with an underlying medical condition, were at increased risk (p<0.05) of becoming a secondary case. The overall secondary attack rate among the 262 susceptible household contacts was 30.2% (95% CI: 12.6-52.2). The median serial interval for pH1N1 transmission was 3.4 days (95% CI: 2.9-3.9).

CONCLUSIONS

The identified transmission characteristics of pH1N1 among Canadian households differ slightly from other previously reported North American estimates, but are in keeping with historical transmission rates of pandemic influenza viruses.

Genetic evidence for involvement of the IL23 pathway in Thai psoriatics

A recent genome-wide association analysis of psoriasis identified IL12B and IL23R as significantly associated with psoriasis. Here we report association test results of a Thai cohort consisting of 206 psoriasis cases and 114 controls. The IL23R SNPs rs7530511 and rs11209026, and IL12B SNPs rs3212227 and rs6887695 were genotyped using Taqman assays. Data were analyzed using a logistic regression model for linear trend of association. One of the IL23R markers, rs7530511, was marginally significant (P = 0.017). The other IL23R marker, rs11209026, was not polymorphic. One of the IL12B markers, rs3212227, showed significant association with psoriasis (OR = 1.64, P = 0.0058) while the other, rs6887695, did not (OR = 1.29, P = 0.12). Haplotype analysis of the two IL12B SNPs yielded highly significant association (P = 0.00081, OR = 1.73). These results showed that IL12B is an important genetic factor in psoriasis pathogenesis in the Thai population, with an association strong enough to yield significant confirmatory evidence using a modest sample size. Together with previously reported evidence for IL12B association in Caucasian, Japanese, and Chinese psoriatics, our results support the hypothesis that genes encoding components of the IL23-mediated inflammatory pathway are important determinants of psoriasis pathogenesis across multiple racial groups.

Prevalence of self-reported neck-shoulder-arm pain and concurrent low back pain or psychological distress: time-trends in a general population, 1990-2006

STUDY DESIGN

Analysis of repeated cross-sectional surveys.

OBJECTIVE

To investigate the prevalence of neck-shoulder-arm pain and concurrent low back pain and psychological distress in a geographical area over a 16-year period.

SUMMARY OF BACKGROUND DATA

A large number of studies have shown that nonspecific neck, shoulder, and arm pain is a very common symptom in the general population. However, few studies have followed the prevalence of neck-shoulder-arm pain within a geographical area, in order to investigate time-trends.

METHODS

This study provides an analysis of questionnaire data collected every 4 years between 1990 and 2006 on the prevalence of neck-shoulder-arm pain and concurrent low back pain or psychological distress in the County of Stockholm, Sweden (response rate: 61%-69%). All individuals aged 21 to 64 years (n = 1976-26,611) were included in the study.

RESULTS

Over the 16-year period, the prevalence of self-reported neck-shoulder-arm pain rose slightly, from 22.8% to 25.0% among females (prevalence rate ratio [PRR]: 1.10) and from 12.8% to 15.4% among males (PRR: 1.21). The prevalence of neck-shoulder-arm pain with concurrent low back pain also rose slightly, from 8.4% to 10.8% among females (PRR: 1.28) and from 5.3% to 6.6% among males (PRR: 1.24). In contrast, the prevalence of neck-shoulder-arm pain with concurrent psychological distress rose more substantially, from 4.4% to 8.5% among females (PRR: 1.91) and from 2.0% to 4.3% among males (PRR: 2.18). All prevalence rates rose between 1990 and 2002, and decreased in 2006 compared to 2002. The gender gap in prevalence did not change over time.

CONCLUSION

Although the prevalence of neck-shoulder-arm pain and concurrent symptoms decreased in 2006 compared to 2002, it is still too early to conclude that we have reached and passed the peak of the "epidemic" of neck-shoulder-arm pain.

Trends in the magnitude of educational inequalities in health in Estonia, Latvia, Lithuania and Finland during 1994–2004

BACKGROUND

Socioeconomic inequalities in health in the Baltic countries are possibly increasing due to concomitant pressures. This study compared time trends from 1994 to 2004 in the pattern and magnitude of educational inequalities in health in Estonia, Latvia, Lithuania and Finland.

METHODS

The data were gathered from cross-sectional postal surveys of the Finbalt project, conducted every second year since 1994 on adult populations (aged 20-64 years) in Estonia (n=9049), Latvia (n=7685), Lithuania (n=11,634) and Finland (n=18,821). Three self-reported health indicators were used: (i) less than good perceived health, (ii) diagnosed diseases, and (iii) symptoms.

RESULTS

The existing educational inequalities in health in three Baltic countries and Finland remained generally stable over time from 1994 to 2004. Also, the overall prevalence of all three health indicators was generally stable, but in the Baltic countries improvement in perceived health was mainly found among the better-educated men and women. Diagnosed diseases increased in the Baltic countries, except Lithuania, where diseases decreased among the better-educated women. Symptoms increased among the better-educated Estonian and Finnish women.

CONCLUSIONS

The period from 1994 to 2004 of relative stabilization since the worst conditions of the social transition has not been followed by notable changes in self-reported health, and this appears to be the situation across all educational groups in the Baltic countries. While health inequalities did not markedly change, substantial inequalities do remain, and there were indications of favourable developments mainly among the better-educated respondents. The factors contributing towards increasing health inequalities may only be visible in the future.

Adverse effects of antifungal therapies in invasive fungal infections: review and meta-analysis

Amphotericin B is the main therapeutic agent for the treatment of invasive fungal infections; however, it is associated with significant toxicities that limit its use. Other systemic antifungal agents have been developed to improve tolerability while maintaining the efficacy profile of conventional amphotericin B. Fifty-four studies involving 9,228 patients were assessed for the frequency of adverse effects of the main systemic antifungal agents. While the results suggest that liposomal amphotericin B is the least nephrotoxic of the lipid formulations (14.6%), that conventional amphotericin B is the most nephrotoxic (33.2%), and that itraconazole is the most hepatotoxic (31.5%), the lack of standard definitions of antifungal-related adverse effects limits the validity of these results. Furthermore, heterogeneous patient pools and differing protocols make it difficult to draw direct comparisons between studies. With the advent of newer classes of systemic antifungal agents, future trials should conform to definitions that are universally applicable and clinically relevant to allow for such comparisons and to enable evidence-based decision-making.

The natural history of developmental dysplasia of the hip: sonographic findings in infants of 1-3 months of age

The natural history of sonographic developmental dysplasia of the hip was determined in a population-based study in which 5170 infants were screened by ultrasound using Graf's method. Of the normal hips at the age of 1 month, 99.6% were still normal at the age of 3 months. Of the immature type IIa/IIa+ and type IIa- hips, if untreated, 95.3 and 84.4% had become normal, respectively. Of the infants with type IIc, D and III/IV hips at the age of 1 month 70, 58.3 and 90.9% were treated, respectively. This study shows that normal hips remain normal in nearly 100% of cases, but development to abnormality is possible. It shows also that most of the immature hips at the age of 1 month become normal without treatment. Although treatment seems to be indicated in the majority of sonographically abnormal hips, the occurrence of overtreatment could not be excluded in our study.

Adverse effects of antifungal therapies in invasive fungal infections: review and meta-analysis

Amphotericin B is the main therapeutic agent for the treatment of invasive fungal infections; however, it is associated with significant toxicities that limit its use. Other systemic antifungal agents have been developed to improve tolerability while maintaining the efficacy profile of conventional amphotericin B. Fifty-four studies involving 9,228 patients were assessed for the frequency of adverse effects of the main systemic antifungal agents. While the results suggest that liposomal amphotericin B (L-AmB) is the least nephrotoxic of the lipid formulations (14.6%), that conventional amphotericin B (AmB) is the most nephrotoxic (33.2%), and that itraconazole is the most hepatotoxic (31.5%), the lack of standard definitions of antifungal-related adverse effects limits the validity of these results. Furthermore, heterogeneous patient pools and differing protocols make it difficult to draw direct comparisons between studies. With the advent of newer classes of systemic antifungal agents, future trials should conform to definitions that are universally applicable and clinically relevant to allow for such comparisons and to enable evidence-based decision-making.

Grading a developmental continuum—elegy on the rise and fall of the endometrial biopsy

Due to the original study design the frequency distribution of the slide categories sent to each of the three expert pathologists was essentially bimodal. The intraclass correlation coefficient for the 1-14 continuous categories reveals excellent agreement (0.82), whereas the kappa statistic for the dichotomized outcomes (>2 day lag) is poor (0.54). The discrepancy between the intraclass correlation coefficient and kappa values seems to be due to the bimodal distribution of the slide ratings. Some impartial mechanism was needed to make an unbiased selection of the slides used for endometrial dating. Imprecision in endometrial dating is due primarily to the limitations of the instrument and not the observer. Maturation stage of the endometrium is not critical for predicting a successful pregnancy.

Use of oral contraceptives and hormone replacement therapy in the WHO MONICA project

AIMS

To compare menopausal age and the use of oral contraceptives (OC) and hormonal replacement therapy (HRT) between the 32 populations of the WHO MONICA Project, representing 20 different countries.

METHODS

Using a uniform protocol, age at menopause and the use of OC and HRT was recorded in a random sample of 25-64 year-old women attending the final MONICA population cardiovascular risk factor survey between 1989 and 1997. A total of 39,120 women were included.

RESULTS

There were wide variations between the populations in the use of OC and HRT. The use of OC varied between 0 and 52% in pre-menopausal women aged 35-44 years, Central and East Europe and North America having the lowest and West Europe and Australasia the highest prevalence rates. Among post-menopausal women between 45 and 64 years, the prevalence of HRT use varied from 0 to 42%. In general, the use of HRT was high in Western and Northern Europe, North America and Australasia and low in Central, Eastern and Southern Europe and China. With the exception of Canada (45 years), the mean age at menopause differed only little (ranging from 48 to 50 years) between the populations.

CONCLUSION

The use of OC and HRT varies markedly between populations, in general following a regional pattern. Whereas, the prevalence rates are mostly similar within a country, there are remarkable differences even between neighbouring countries, reflecting nation-specific medical practice and public attitudes that are not necessarily based on scientific evidence.

Asymptomatic peripheral arterial occlusive disease predicted cardiovascular morbidity and mortality in a 7-year follow-up study

OBJECTIVE

Asymptomatic peripheral arterial occlusive disease (PAOD) is a common atherosclerotic disorder among the elderly population. Scarce data are available on the risk of nonfatal and fatal cardiovascular diseases in these subjects. We investigated cardiovascular morbidity and mortality of asymptomatic PAOD subjects.

STUDY DESIGN AND SETTING

A sample of 3649 subjects (40-78 years of age) was selected in collaboration with 18 general practice centers and followed up after the initial screening (mean follow-up time 7.2 years). Asymptomatic PAOD was determined by means of the ankle-brachial pressure index (ABPI). Main outcome measures were nonfatal cardiovascular events and mortality.

RESULTS

Cox proportional hazard models showed that asymptomatic PAOD was significantly associated with cardiovascular morbidity (hazard ratio [HR] 1.6, 95% confidence interval [CI] 1.3-2.1), total mortality (HR 1.4, 95% CI 1.1-1.8), and cardiovascular mortality (HR 1.5, 95% CI 1.1-2.1).

CONCLUSION

Asymptomatic PAOD is a significant predictor of cardiovascular morbidity and mortality. In high-risk subjects, measurement of the ABPI provides valuable information on future cardiovascular events.

Optimal designs of two-stage studies for estimation of sensitivity, specificity and positive predictive value

The cost efficiency of estimation of sensitivity, specificity and positive predictive value from two-stage sampling designs is considered, assuming a relatively cheap test classifies first-stage subjects into several categories and an expensive gold standard is applied at stage two. Simple variance formulae are derived and used to find optimal designs for a given cost ratio. The utility of two-stage designs is measured by the reduction in variances compared with one-stage simple random designs. Separate second-stage design is also compared with proportional allocation (PA). The maximum percentage reductions in variance from two-stage designs for sensitivity, specificity and positive predictive value estimation are P per cent, (1-P) per cent and W, respectively, where P is the population prevalence of disease and W the population percentage of test negatives. The optimum allocation of stage-two resources is not obvious: the optimum proportion of true cases at stage two may even be less than under PA. PA is near optimal for sensitivity estimation in most cases when prevalence is low, but inefficient compared with the optimal scheme for specificity.

Incidence of and risk factors for asymptomatic peripheral arterial occlusive disease: a longitudinal study

The current study describes the age- and sex-specific incidence rates and risk factors for asymptomatic and symptomatic peripheral arterial occlusive disease (PAOD) among 2,327 subjects and the incidence of intermittent claudication in asymptomatic PAOD subjects. The study population was selected from 18 general practice centers in the Netherlands. PAOD was assessed with the ankle-brachial blood pressure index, and intermittent claudication was assessed with a modified version of the Rose questionnaire. After 7.2 years, the overall incidence rate for asymptomatic PAOD, using the person-years method, was 9.9 (95% confidence interval (CI): 7.3, 18.8) per 1,000 person-years at risk. The rate was 7.8 (95% CI: 4.9, 20.3) for men and 12.4 (95% CI: 7.7, 24.8) for women. For symptomatic PAOD, the incidence rate was 1.0 (95% CI: 0.7, 7.5) overall, 0.4 (95% CI: 0.3, 10.0) for men, and 1.8 (95% CI: 1.0, 10.3) for women. Multivariate analyses showed that increasing age, smoking, hypertension, and diabetes mellitus were the most important risk factors. The overall incidence rate for intermittent claudication among PAOD subjects who were asymptomatic at baseline was 90.5 per 1,000 person-years at risk (95% CI: 36.4, 378.3). The incidence of asymptomatic PAOD was higher than the incidence of symptomatic PAOD, with women developing PAOD more often than men. In the development of preventive strategies, modification of atherosclerotic risk factors, such as smoking, hypertension, and diabetes, should be the main goals.

Frequency of phobic disorder in a community sample of young adolescents

OBJECTIVE

To investigate the frequency and phenomenology of clinical, subsyndromal, and subthreshold phobias in young adolescents.

METHODS

A two-stage epidemiological study originally designed to investigate adolescent depression was conducted between 1986 and 1988 in the southeastern United States. In the first stage, a self-report depressive symptom questionnaire was administered to a community sample of 3,283 adolescents. In the diagnostic stage, the Schedule for Affective Disorders and Schizophrenia for School-Age Children and the Children's Global Assessment Scale were administered to 487 mother-child pairs.

RESULTS

Prevalence rates of clinical, subsyndromal, and subthreshold phobia were 2.3%, 14.5%, and 22.2%, respectively. One-year incidence rates were 0.4%, 8.0%, and 16.9%, with 43.0% of phobic subjects categorized at the same or a more severe level after a year. Females, blacks, subjects not living with both biological parents, and older adolescents were more likely to meet the diagnostic criteria for clinical phobia. The majority (77%) of subjects with clinical phobia experienced multiple phobias. Subsyndromal (52%) and subthreshold (74%) phobics were more likely to experience simple phobias only.

CONCLUSIONS

Phobic symptoms are relatively common at a moderate level and in the majority of adolescents are somewhat transitory in nature. Characteristic symptomatology and comorbidity may facilitate earlier identification of subjects at risk of persistent symptomatology and in need of treatment.

Screening for stratification in two-phase ('two-stage') epidemiological surveys

Screening is undertaken not only for the purpose of giving therapeutic treatment to those among screen positive subjects found to be diagnosis positive, but it is also used in epidemiology as the first phase of multi-phase sampling designs. We review the use of such designs in epidemiology, and in psychiatric epidemiology in particular, focusing on two-phase or double sampling. We then compare a variety of approaches to the statistical analysis of data from such designs including the use of sampling weights, Gibbs sampling, full maximum likelihood for random effects logistic regression and a simple E-M algorithm for incomplete data. The methods are illustrated using data from a recent multi-phase study of psychiatric morbidity in northern Spain.