Since 2004, a surveillance system provides counts, almost in real time, of the number of deaths per day occurring on the Island of Montreal. The validity of this monitoring tool and its ability to detect spikes in daily deaths, such as can occur due to heat waves, have been evaluated.
Comparison of the number of deaths per day recorded in the monitoring system with the number of deaths per day recorded in the official record of deaths in Quebec for 134 days of 2004.
The monitoring system is accurate (for over 73% of days, the difference in the number of deaths between the two files falls within a range of +/-3 deaths given an average of 43 deaths per day). The system identifies more than 80% of all deaths and is efficient in identifying days with excess deaths that are 20% above the average.
This novel monitoring system, based on data used mainly for management of medical services, meets contemporary public health requirements in terms of early detection of unusual health events.
Associations between monthly counts of all laboratory-confirmed cases of salmonellosis in Arkhangelsk, northern Russia, from 1992 to 2008 and climatic variables with lags 0-2 were studied by three different models. We observed a linear association between the number of cases of salmonellosis and mean monthly temperature with a lag of 1 month across the whole range of temperatures. An increase of 1 °C was associated with a 2·04% [95% confidence interval (CI) 0·25-3·84], 1·84% (95% CI 0·06-3·63) and 2·32% (95% CI 0·38-4·27) increase in different models. Only one of the three models suggested an increase in the number of cases, by 0·24% (95% CI 0·02-0·46) with an increase in precipitation by 1 mm in the same month. Higher temperatures were associated with higher monthly counts of salmonellosis while the association with precipitation was less certain. The results may have implications for the future patterns of enteric infections in northern areas related to climate change.
Epidemiologic studies on adverse health effects of cellular telephone use have assessed exposure either by self-reported use based on questionnaire data or by using data on subscriptions for a cellular telephone provided by network operators. With the latter approach, subjects are misclassified when they regularly use a cellular telephone subscribed in someone else's or in a company name or when they subscribe for a cellular telephone which they use only occasionally. Self-reported use is hampered by recall difficulties and possible differential participation by exposure. In Denmark, we conducted a retrospective cohort study of cellular telephone subscribers (including the entire Danish population) and a case-control study on brain tumors and cellular telephone use (with 1355 participants) and, thus, had the opportunity to compare the two exposure measures with two large-scale data sets, using self-reported use as a "gold standard." Overall, there was a fair agreement (kappa value of 0.30, 95% confidence interval 0.23-0.36), with a low sensitivity (30%) and a high specificity (94%). Agreement was slightly better for controls, and low-grade glioma cases compared to high-grade glioma cases and meningioma cases. A comparison of odds ratios (OR) of the case-control data set based on either self-reported use or on subscriber data shows no major differences, giving OR of 0.7 and 0.6 for acoustic neuroma, 0.9 and 1.1 for glioma and 0.9 and 0.7 for meningioma. A discussion of the two exposure measures reveals that they both have limitations with regard to a potential underestimation of an association and there is some concern whether they are good enough to allow a detection of possibly only subtle changes in risk. These limitations can be minimized in prospective follow-up studies.
This paper presents a large-scale cross-sectional study of Danish children's early language acquisition based on the Danish adaptation of the MacArthur-Bates Communicative Development Inventories (CDI). Measures of validity and reliability imply that the Danish adaptation of the American CDI has been adjusted linguistically and culturally in appropriate ways which makes it suitable for tapping into Danish children's language acquisition. The study includes 6,112 randomly selected children in the age of 0 ; 8 to 3 ; 0, and results related to the development of early gestures, comprehension and production of words as well as grammatical skills, are presented.
Several studies show that asthma mortality in children and adolescents increased until the mid-1990s, after which it has slightly decreased worldwide. The objective of this study was to describe the mortality rates of childhood asthma in Finland, and to analyze patient characteristics to identify predisposing factors for fatal asthma exacerbation among children and adolescents during 1976-1998 (2004). All death certificates where asthma or related respiratory tract disease was coded as the underlying cause of death were reviewed for those under 20 years of age. Health care records and autopsy reports were evaluated to validate the cause of death and to identify any predisposing factors. In all, there had been 28 asthma deaths. The validity of the death certificates proved to be good as only 7% were misclassified. Death occurred either in the very young children or adolescents: the median age in the group of 12 years (n = 13) was 18.1 years. The fatal exacerbations occurred mostly during summer and early autumn. Clinical triggers, recorded for 14/22 patients with available patient records, included respiratory infection, (12) use of ibuprofen despite known allergy (1), and exercise after visiting a horse stable (1). The severity of the disease was discernible in 21 patients: severe in 15, moderate in 5, and mild in 1 patient. Inhaled corticosteroids were not used as maintenance or periodic therapy in 12/22 patients, of whom 4 had died during the 1990s. In conclusion, asthma mortality in Finnish children and adolescents was rare and its incidence remained stable. The validity of the death certificate diagnoses proved to be good. Poor asthma management and non or undertreatment with inhaled corticosteroids were risk factors for fatal asthma.
In recent years several Danish studies of the etiology, time trends and long-term health consequences of cryptorchidism have relied on diagnoses and surgical treatments registered in the National Patient Registry. We evaluated the diagnostic accuracy of these registry data.
According to the Danish National Patient Registry, 16,168 males were diagnosed with cryptorchidism and 9,244 surgical treatments for cryptorchidism were performed between January 1, 1995 and October 10, 2009. We randomly selected 500 diagnosed cases, of which 284 had been managed surgically. We requested the medical records from the departments making the diagnoses and performing the surgery.
We successfully retrieved medical records for 452 diagnosed cases (90%) and 249 operations (88%). Overall positive predictive value of a registry diagnosis of cryptorchidism was 80% (95% CI 77-84) using the testicular position described by the physician performing the clinical examination as the gold standard. Similarly the positive predictive value of the surgical treatment registration was 99% (95% CI 98-100) using the type of procedure performed.
The data on cryptorchidism in the Danish National Patient Registry are quite accurate. In etiological research the limited misclassification will in most cases only slightly attenuate estimates of the true relative association. Thus, the registry has the potential to serve as a valuable research tool, although caution should be exercised when studying time trends or geographical differences.
Norwegian Centre for Quality Improvement of Primary Care Laboratories, Section for General Practice, Department of Public Health and Primary Health Care, University of Bergen, Bergen, Norway. email@example.com
The analytical quality of self-monitoring of blood glucose (SMBG) can be affected by environmental conditions such as temperature. The objective of this study was to determine the influence of (1) a shift in the ambient temperature immediately before measurement and (2) taking measurements in the lower and upper part of the operating temperature range.
Nine different SMBG systems on the Norwegian market were tested with heparinized venous blood (4.8 and 19.0?mmol/L). To test the shift in ambient temperature effect, the glucometer and strips were equilibrated for 1?h at 5°C or 1?h at 30°C before the meter and strips were moved to room temperature, and measurements were performed after 0, 5, 10, 15, and 30?min. To test the lower and upper temperature range, measurements were performed at 10°C and at 39°C after 1?h for temperature equilibration of the glucometer and strips. All these measurements were compared with measurements performed simultaneously on a meter and strips kept at room temperature the whole time.
Six of nine SMBG systems overestimated and/or underestimated the results by more than 5% after moving meters and strips from 5°C or 30°C to room temperature immediately before the measurements. Two systems underestimated the results at 10°C. One system overestimated and another underestimated the results by more than 5% at 39°C.
The effect on analytical performance was most pronounced after a rapid shift in the ambient temperature. Therefore patients need to wait at least 15?min for temperature equilibration of affected meters and strips before measuring blood glucose.
The heterophil to lymphocyte (HL) ratio in the peripheral blood is increasingly being recognized as a reliable indicator of stress in birds. In this study we examined whether HL ratio, as well as the proportion of heterophils and lymphocytes, varied systematically with sampling time, date, age, climate conditions or with measures of maternal investment in female tree swallows (Tachycineta bicolor) over three breeding seasons. We found that HL ratios showed significant annual variation, which appeared to be driven by annual changes in the proportion of heterophils. HL ratios were higher among those females laying larger clutches, suggesting a potential cost of reproduction. Variation in body condition also appeared to affect stress levels of females, as decreases in body condition were associated with elevated HL ratios. Among females that we sampled over multiple breeding seasons, we were unable to detect significant repeatability for both HL ratios and proportion of heterophils, although proportion of lymphocytes showed low but significant repeatability within individuals. We therefore suggest that caution should be exercised in using these measures for illustrating the inherent quality or health of individuals over time frames beyond the current breeding attempt, or as predictors of future reproductive potential.
The reliability and validity of proxy respondent information in the Canadian Hospitals Injury Reporting and Prevention Program surveillance system was assessed. A standardized form was used to collect data on injury date, location, context (activity at the time), breakdown factor (what went wrong), mechanism, product involvement, safety precaution use, and motor vehicle involvement. The test-retest method determined reliability, with the kappa coefficient quantifying agreement between respondent information provided in the emergency department and later during a telephone interview. Of 421 eligible respondents, 325 (77%) completed the telephone interview, with a median time to interview of 33 hours (range 24-70 hours). Agreement was high for all items; kappa coefficients ranged from 0.79 (substantial agreement) to 1.00 (perfect agreement). Reliability was not significantly modified by respondent view of the injury event, age of the child, language of the form, or level of respondent education. Validity was determined by measuring the agreement between respondent information and that provided by an independent witness. Witness information was considered to represent the truth. Of the 140 injury events selected, 92 (66%) had the form completed by both the original respondent and an independent witness. Kappa coefficients were greater than 0.65 for all but one item (safety precaution use), and the positive predictive value of respondent information for item categories whose prevalence was > or = 0.25 ranged from 0.82 to 0.95. The authors conclude that proxy respondent data on childhood injury are both reliable and valid.