Michelle E. Kruijshaar

Lifetime prevalence estimates of major depression: an indirect estimation method and a quantification of recall bias.

The measurement of lifetime prevalence of depression in cross-sectional surveys is biased by recall problems. We estimated it indirectly for two countries using modelling, and quantified the underestimation in the empirical estimate for one. A microsimulation model was used to generate population-based epidemiological measures of depression. We fitted the model to 1-and 12-month prevalence data from the Netherlands Mental Health Survey and Incidence Study (NEMESIS) and the Australian Adult Mental Health and Wellbeing Survey. The lowest proportion of cases ever having an episode in their life is 30% of men and 40% of women, for both countries. This corresponds to a lifetime prevalence of 20 and 30%, respectively, in a cross-sectional setting (aged 15–65). The NEMESIS data were 38% lower than these estimates. We conclude that modelling enabled us to estimate lifetime prevalence of depression indirectly. This method is useful in the absence of direct measurement, but also showed that direct estimates are underestimated by recall bias and by the cross-sectional setting.

Increasing reports of non-tuberculous mycobacteria in England, Wales and Northern Ireland, 1995-2006

BackgroundNon-tuberculous mycobacteria have long been identified as capable of causing human disease and the number at risk, due to immune-suppression, is rising. Several reports have suggested incidence to be increasing, yet routine surveillance-based evidence is lacking. We investigated recent trends in, and the epidemiology of, non-tuberculous mycobacterial infections in England, Wales and Northern Ireland, 1995-2006.MethodsHospital laboratories voluntarily report non-tuberculous mycobacterial infections to the Health Protection Agency Centre for Infections. Details reported include age and sex of the patient, species, specimen type and source laboratory. All reports were analysed.ResultsThe rate of non-tuberculous mycobacteria reports rose from 0.9 per 100,000 population in 1995 to 2.9 per 100,000 in 2006 (1608 reports). Increases were mainly in pulmonary specimens and people aged 60+ years. The most commonly reported species was Mycobacterium avium-intracellulare (43%); M. malmoense and M. kansasii were also commonly reported. M. gordonae showed the biggest increase over the study period rising from one report in 1995 to 153 in 2006. Clinical information was rarely reported.ConclusionsThe number and rate of reports increased considerably between 1995 and 2006, primarily in older age groups and pulmonary specimens. Increases in some species are likely to be artefacts but real changes in more pathogenic species, some of which will require clinical care, should not be excluded. Enhanced surveillance is needed to understand the true epidemiology of these infections and their impact on human health.

Increase in extrapulmonary tuberculosis in England and Wales 1999–2006

Background: Extrapulmonary tuberculosis appears to be increasing in England and Wales. The trends in extrapulmonary tuberculosis and factors associated with these trends were examined. Methods: National tuberculosis surveillance data from 1999–2006 for England and Wales were used, including demographic, clinical and laboratory information. Trends in the proportion of tuberculosis cases with extrapulmonary disease were investigated using the χ2 trend test and associated factors using logistic regression. Results: Among all the cases of tuberculosis, the proportion with extrapulmonary disease increased from 48% in 1999 (2717 cases) to 53% in 2006 (4205 cases, p<0.001). Regression analysis showed that the rise in extrapulmonary disease was associated with an increase in the proportion of non-UK born cases (odds ratio 2.7, 95% CI 2.6 to 2.8). A more than threefold increase was observed in the proportion of all tuberculosis cases with miliary tuberculosis from 0.7% of all cases (38 cases) to 2.2% (180 cases, p<0.001). This rise was not associated with changes in place of birth or in any of the other risk factors identified. Conclusions: The proportion of cases with extrapulmonary disease has increased over the study period. To a large extent this is due to an increasing proportion of non-UK born cases. Reasons for the rise in miliary tuberculosis require further investigation. Clinicians should have a higher index of clinical suspicion of extrapulmonary tuberculosis in non-UK born cases.

Effect of enzyme therapy and prognostic factors in 69 adults with Pompe disease: an open-label single-center study

BackgroundEnzyme replacement therapy (ERT) in adults with Pompe disease, a progressive neuromuscular disorder, is of promising but variable efficacy. We investigated whether it alters the course of disease, and also identified potential prognostic factors.MethodsPatients in this open-label single-center study were treated biweekly with 20 mg/kg alglucosidase alfa. Muscle strength, muscle function, and pulmonary function were assessed every 3–6 months and analyzed using repeated-measures ANOVA.ResultsSixty-nine patients (median age 52.1 years) were followed for a median of 23 months. Muscle strength increased after start of ERT (manual muscle testing 1.4 percentage points per year (pp/y); hand-held dynamometry 4.0 pp/y; both p < 0.001). Forced vital capacity (FVC) remained stable when measured in upright, but declined in supine position (−1.1 pp/y; p = 0.03). Muscle function did not improve in all patients (quick motor function test 0.7 pp/y; p = 0.14), but increased significantly in wheelchair-independent patients and those with mild and moderate muscle weakness.Relative to the pre-treatment period (49 patients with 14 months pre-ERT and 22 months ERT median follow-up), ERT affected muscle strength positively (manual muscle testing +3.3 pp/y, p < 0.001 and hand-held dynamometry +7.9 pp/y, p < 0.001). Its effect on upright FVC was +1.8 pp/y (p = 0.08) and on supine FVC +0.8 (p = 0.38). Favorable prognostic factors were female gender for muscle strength, and younger age and better clinical status for supine FVC.ConclusionsWe conclude that ERT positively alters the natural course of Pompe disease in adult patients; muscle strength increased and upright FVC stabilized. Functional outcome is probably best when ERT intervention is timely.

The use of models in the estimation of disease epidemiology

OBJECTIVE To explore the usefulness of incidence-prevalence-mortality (IPM) models in improving estimates of disease epidemiology. METHODS Two artificial and four empirical data sets (for breast, prostate, colorectal, and stomach cancer) were employed in IPM models. FINDINGS The internally consistent artificial data sets could be reproduced virtually identically by the models. Our estimates often differed considerably from the empirical data sets, especially for breast and prostate cancer and for older ages. Only for stomach cancer did the estimates approximate to the data, except at older ages. CONCLUSION There is evidence that the discrepancies between model estimates and observations are caused both by data inaccuracies and past trends in incidence or mortality. Because IPM models cannot distinguish these effects, their use in improving disease estimates becomes complicated. Expert opinion is indispensable in assessing whether the use of these models improves data quality or, inappropriately, removes the effect of trends.

Monitoring tuberculosis treatment outcome: analysis of national surveillance data from a clinical perspective

Background: In 1998, the World Health Organization (WHO) and the International Union Against Tuberculosis and Lung Disease (IUATLD) published recommendations standardising the evaluation of tuberculosis treatment outcome in Europe. These guidelines fail to account for clinically appropriate alterations in the management of patients. Objectives: To evaluate tuberculosis treatment outcome in England, Wales and Northern Ireland by redefining the outcome criteria and investigate factors associated with unsuccessful treatment outcome 12 months after notification. Methods: This was a prospective analysis of a cohort of patients diagnosed in England, Wales and Northern Ireland and reported to the Enhanced Tuberculosis Surveillance system in 2001 and 2002. Proportions of success and failure were calculated based on a new set of criteria following discussion with clinicians treating tuberculosis cases. Logistic regression was used to study risk factors for unsuccessful treatment outcome. Results: 13 048 cases were notified in the study period. Of the 2676 that were identified as new sputum smear positive pulmonary cases, 2209 (82.5%) had treatment outcome data reported. Using the WHO/IUATLD criteria, 76.8% were classified as successful. In contrast, applying the new criteria, the success rate was 87.5%. This rate exceeds the 85% success target set by the WHO. Risk factors for unsuccessful treatment outcome included male sex (OR 1.27; 95% CI 1.08 to 1.49), being elderly (p trend <0.001), having pulmonary tuberculosis (OR 1.28; 95% CI 1.08 to 1.53) and having resistance to any antituberculosis drug (OR 1.90; 95% CI 1.44 to 2.52). Conclusion: The proportion of tuberculosis cases with a successful treatment outcome exceeded the target of 85% success rate based on the modified outcome categories. Although the tuberculosis treatment outcome criteria set by WHO/IUATLD appear to be clear, they mix measures of process and outcome. Further refinement may be necessary in low incidence high income countries, especially those with a high mortality among the elderly.

Increasing antituberculosis drug resistance in the United Kingdom: analysis of National Surveillance Data.

Objective To identify recent trends in, and factors associated with, resistance to antituberculosis drugs in England, Wales, and Northern Ireland. Design Cohort of tuberculosis cases reported to the enhanced tuberculosis surveillance system matched to data on drug susceptibility and national strain typing data. Setting England, Wales, and Northern Ireland 1998-2005. Main outcome measures Unadjusted and adjusted odds ratios for drug resistance and associated factors. Proportion of multidrug resistant tuberculosis cases clustered. Results 28 620 culture confirmed cases were available for analysis. The proportion of cases resistant to isoniazid increased from 5% to 7%. Rifampicin resistance increased from 1.0% to 1.2% and multidrug resistance from 0.8% to 0.9%. Ethambutol and pyrazinamide resistance remained stable at around 0.4% and 0.6%, respectively. Regression analyses showed a significant increase in isoniazid resistance outside London (odds ratio 1.04, 95% confidence interval 1.01 to 1.07, a year, associated with changes in age (0.98, 0.98 to 0.99, a year), place of birth (1.49, 1.16 to 1.92), and ethnicity (P<0.05). In London, the rise (1.05, 1.02 to 1.08, a year) was related mainly to an ongoing outbreak. Increases in rifampicin resistance (1.06, 1.01 to 1.11, a year) and multidrug resistance (1.06, 1.00 to 1.12, a year) were small. A fifth of patients with multidrug resistant tuberculosis in 2004-5 had indistinguishable strain types, and one case was identified as extensively drug resistant. Conclusions The rise in isoniazid resistance reflects increasing numbers of patients from sub-Saharan Africa and the Indian subcontinent, who might have acquired resistance abroad, and inadequate control of transmission in London. The observed increases highlight the need for early case detection, rapid testing of susceptibility to drugs, and improved treatment completion.

Has the burden of depression been overestimated

OBJECTIVE To investigate whether high estimates of the burden of depression could be attributed to an overestimation of disability weights (reflecting more severe disability). METHODS We derived disability weights that were tailored to prevalence data. Empirical disability data from a Dutch community survey was used to describe three classes of severity of depression and their proportional prevalence. We obtained valuations from experts for each class and calculated the overall disability weight for depression. FINDINGS Expert valuations were similar to those of previous studies. The overall disability weight for depression was similar to other studies except the 1994 Dutch Burden of Disease Calculation, which it exceeded by 73%. The lower Dutch 1994 disability weight resulted from an overestimation of the proportion of mild cases of depression by experts (60% versus 27% observed in the empirical data used in the present study). CONCLUSION This study found no indication that disability associated with depression was overestimated. The Dutch example showed the importance of tailoring disability weights to epidemiological data on prevalence.

Tuberculosis and HIV co-infection in European Union and European Economic Area countries

In order to ensure the availability of resources for tuberculosis (TB) and HIV management and control, it is imperative that countries monitor and plan for co-infection in order to identify, treat and prevent TB–HIV co-infection, thereby reducing TB burden and increasing the years of healthy life of people living with HIV. A systematic review was undertaken to determine the burden of TB–HIV infection in the European Union (EU) and European Economic Area (EEA). Data on the burden of HIV infection in TB patients and risk factors for TB–HIV co-infection in the EU/EEA were extracted from studies that collected information in 1996 and later, regardless of the year of initiation of data collection, and a narrative synthesis presented. The proportion of HIV-co-infected TB patients varied from 0 to 15%. Western and eastern countries had higher levels and increasing trends of infection over time compared with central EU/EEA countries. Groups at higher risk of TB–HIV co-infection were males, young adults, foreign-born persons, the homeless, injecting drug users and prisoners. Further research is needed into the burden and associated risk factors of co-infection in Europe, to help plan effective control measures. Increased HIV testing of TB patients and targeted and informed strategies for control and prevention could help curb the co-infection epidemic.

The burden of TB–HIV in the EU: how much do we know? A survey of surveillance practices and results

Information on the burden of tuberculosis (TB)–HIV co-infection is critical for the planning and evaluation of TB–HIV control and treatment strategies. This study assessed current practices in countries of the European Union (EU) and European Economic Area (EEA) for monitoring HIV co-infection in TB surveillance systems, countries’ current co-infection burden and associated clinical practice. An online survey was distributed to all national TB surveillance nominated European Centre for Disease Prevention and Control contact points in the EU/EEA. We received 25 responses from 30 countries (83% response rate). Patients’ HIV status was collected in 18 out of the 25 TB surveillance systems, usually via clinician reporting (16 out of 18 surveillance systems). Although most countries recommended routine testing of TB patients for HIV, the proportion actually tested varied from 5% to 90%. The burden of HIV co-infection was found to be elevated in countries with higher levels of HIV testing and higher prevalence of HIV. We suggest that TB–HIV co-infection be monitored in all EU/EEA countries to facilitate the planning and evaluation of TB–HIV control strategies. Strengthening collaboration between TB and HIV clinicians and surveillance departments, and consideration of patient confidentiality restraints would be advantageous. The level of HIV testing in TB patients is low despite national recommendations and testing should be further promoted and monitored.