[Huntington disease in the Valencian Region]

INTRODUCTION

Huntington disease (HD) is a rare neurodegenerative disorder of the central nervous system characterized by unwanted choreatic movements, behavioral and psychiatric disturbances and dementia.

OBJECTIVE

Describe the geographical, age and sex distribution of HD in the Valencia Region (VR) and determine its prevalence and mortality.

MATERIALS AND METHODS

Cross-sectional study for the period 2010-2018. Confirmed cases of HD were identified through the Rare Disease Information System of the VR. Sociodemographic characteristics were described, and the prevalence and mortality rate were obtained.

RESULTS

225 cases were identified, 50.2% women. 52.0% lived in the province of Alicante. 68.9% were verified by their clinical diagnosis. The median age at diagnosis was 54.1 years, 54.7 years in men and 53.0 years in women. The prevalence in 2018 was 1.97/100,000 inhabitants (95%; CI: 0.39-2.37), showing a no significant increasing trend, overall and by sex. 49.8% died, 51.8% men. The median age at death was 62.7 years, being lower in men than in women. The mortality rate in 2018 was 0.32/100,000 inhabitants (95%; CI: 0.32-2.28), with no statistically significant differences.

CONCLUSIONS

The prevalence obtained was within the range estimated by Orphanet (1-9/100,000). A difference between sexes was observed in the diagnosis age. Men are the group with the highest mortality and the earliest age of death. It is a disease with high mortality with an average of 6.5 years between diagnosis and death.

Socioeconomic differences in perinatal health outcomes: perinatal health surveillance through a health-equity prism

Background

Socioeconomic status (SES) is strongly associated with perinatal health outcomes, perpetuating intergenerational health inequalities. Our aim was to assess the utility of population data in Europe to monitor social inequalities in key perinatal health indicators.

Methods

Using the PHIRI federated analysis protocol to aggregate routine birth data from across Europe, we collected data on selected perinatal health indicators by SES from 2015 to 2020. Mothers’ education level (primary/lower secondary; upper secondary; postsecondary) was the preferred SES indicator; if unavailable, parents’ occupation or area-based deprivation scores were provided. The International Standard Classification of Occupations was used to group parents’ occupations into 4 categories, while area-based deprivation scores were measured in quintiles. For each country, we calculated risk ratios (RR) for preterm birth, stillbirth, neonatal death and caesarean delivery (CD) comparing the most with the least disadvantaged group

Results

17 countries provided data on maternal education, 5 on area-based deprivation, 1 on parents’ occupation and 2 could not provide data. For preterm birth, stillbirth and neonatal death, lower SES was associated with worse outcomes with most RR between lowest and highest groups in the range of 1.5 to 3.0. In contrast, in some countries, such as Croatia, Latvia, Lithuania and Spain, CD rates were higher for socially advantaged groups whereas the gradient was reversed in others (Denmark, Luxembourg, the Netherlands and Italy).

Conclusions

European countries can provide perinatal health indicators by SES, revealing marked socioeconomic inequalities in perinatal health. The differing SES gradient between countries for CD raise questions about care organization and clinical practice. Further exploration of the harmonization of differing SES measure across countries is required, while countries that do not monitor SES data should aim to improve existing systems.

Age ranges in breast cancer screening: simulated scenarios and analysis of benefits and harms

Background

The Valencia Region Breast Cancer Screening Programme (VR-BCSP) (Spain) invites women aged 45-69 for mammography every 2 years (y). The aim is to evaluate benefits and harms of 3 age range scenarios of the VR-BCSP according to different adherence rates.

Methods

Long-term impact simulation study (2020-2050) of 3 age range screening scenarios (S) for women ≥40y of the VR in 2020 (n = 1487000): S1, 45-69y (current VR-BCSP scenario); S2, 50-69y (excluding 45-49y) and S3, 45-74y (including 70-74y). A biennial screening interval was considered. The simulations were performed for 4 participation rates: A=current adherence (72.7%), B = +5%, C = +10% and D = +20%. Benefit indicators were: nº of BC in situ and invasive (screened vs. clinically detected), nº of BC deaths and % of BC mortality reduction. Harms indicators were: nº of false positives (FP) and % of overdiagnosis. Screening scenarios were simulated using the EUTOPIA evaluation tool.

Results

Considering the current adherence, a reduction of BC mortality was observed in all scenarios (S1A=30.6%, S2A=27.9%, S3A=32.2%). In S2A the harms decreased vs. S1A: nº of FP (236vs423 x1000) and overdiagnosis (4.9%vs5.0%), but also the benefits: BC mortality reduction (27.9%vs30.6%) and nº of invasive BC screen detected (15/28vs18/25). In S3A vs S1A, an increase of benefits was observed: BC mortality reduction (32.2%vs30.6%) and nº of in situ BC screen detected (5/2vs4/3). On the other hand the nº of FP increased (460vs423 x1000), but overdiagnosis decreased (4.8%vs5.0%). All the results with an increased adherence had similar trend as the previous scenarios, showing a gradual increment in BC mortality reduction. Nevertheless overdiagnosis increase significantly in S3 (5.8% in all adherence increments), being higher than S1 (S1B=5.0%, S1C=4.9%, S1D=5.0%) and S2 (S2B=4.9%, S2C=4.9%, S2D=4.9%).

Conclusions

The wider age range, the greater reduction in BC mortality but also the probability of FP and overdiagnosis.

Key messages

• The wider age range, the greater reduction in BC mortality but also the probability of FP and overdiagnosis.

• This study provides a balance between benefits and harms of different screening scenarios allowing evidence-based decision making.

Folic acid supplementation in the Congenital Anomalies population-based registry in a Spanish Region

Background

The Congenital Anomalies (CA) population-based registry of Valencian Region (RPACCV) has identified 11376 cases, live births (LB) and stillbirths (SB), between 2007-2018 with at least 1 major CA, diagnosed prenatally or up to 1 year old. The Folic acid supplementation (FAS) during the pregnancy is also registered.

Aim

To identify differences in sociodemographic and clinical characteristics and in CA presentation, in cases from RPACCV according to prenatal FAS.

Methods

A cross-sectional study was performed using the RPACCV to identify exposure to FAS (yes/no) in pregnancies with a born (LB and SB) with CA between 2007-2018. Pregnancies with unknown exposure were excluded. Percentages and their 95% confidence intervals (95%CI) of the sociodemographic and clinical characteristics of the cases were determined and compared according to pregnant exposure to FAS. Frequency and its 95%CI of the different CA groups were identified by exposure.

Results

14.1% of pregnancies (1602) were exposed to FAS and 10.4% (1182) were not, 75.5% were excluded. Statistically significant differences weren't found for sociodemographic and clinical characteristics according to exposure. In children of women exposed 1777 CA were identified and 2019 CA in those unexposed. Statistically significant differences were found in these CA groups (shown as % in the exposed/% in the unexposed): Heart defects (7.1%/52.7%), Respiratory (0.2%/1.2%), Digestive (2.3%/5.3%), Genital (2.5%/4.8%), Urinary (3.9%/9.3%), Limb (6.8%/9.4%), Oro-facial clefts (25.4%/2.8%), Eyes, Ears, Face and Neck (3.8%/1.2%).

Conclusions

Several studies identified that FAS prevents from some CA. The fact that in only 25% of pregnant women there is information about FAS, highlight the difficulties of its registration in the clinical documentation. However, with the available information, it was identified that children of unexposed pregnant women presented more CA and from groups with a higher impact on morbidity and mortality.

Key messages

In Spain, Folic acid supplementation doesn’t require a prescription and, as its use is customary prior and during pregnancy, it doesn’t seem to be considered as significant drug exposure in pregnancy. Differences between pregnancies exposed and unexposed to folic acid supplementation were found regarding the number of congenital anomalies presented in their children and its severity.

Portrait of Hungtinton’s Disease in the Valencian Region: a cross-sectional study

Background

Huntington Disease (HD) is a rare neurodegenerative disorder of the central nervous system characterized by involuntary choreic movements and behavioural/psychiatric disorders, which compromises the quality of life.

Objective

To identify the distribution of HD by sex, age and province in the Valencian Region (VR) and to determine its prevalence and mortality rate.

Methods

A cross-sectional epidemiological study was performed. HD's cases between 2010-2018 were identified from the Rare Disease Information System of the VR by selecting codes 333.4 (ICD9) and G10 (ICD10). A descriptive analysis was performed by country of birth, province of residence and sex. Median ages at diagnosis and at death, with interquartile range (IQR), and prevalence and mortality rate, with 95% confidence intervals (95%CI), were obtained.

Results

225 cases were identified: 50.2% women, 52.0% residents in the southernmost province, 92.9% born in Spain and 68.9% confirmed by clinical manifestations. Median age at diagnosis was 54.1 years (IQR:41.1-66.1): 54.7 (IQR:41.2-66.1) in men and 53.0 (IQR:40.5-65.8) in women. Prevalence in 2018 was 2.0/100000 inhabitants (95%CI:0.4-2.4), being higher in women [2.2 (95%CI:0.3-2.8)] than in men [1.8 (95%CI:0.3-2.3)]. Even an increasing trend was observed, significant differences weren't found. 49.8% of cases died during the study, being 51.8% men. The median age at death was 62.7 years (IQR:51.1-74.2), 61.1 (IQR:48.7-72.5) in men and 66.6 (IQR:53.3-76.8) in women. The mortality rate in 2018 in both sexes was 0.3/100000 inhabitants (95%CI:0.3-2.3), significant differences weren't found.

Conclusions

Most of confirmations at registry level were based on clinical manifestations, reinforcing that HD has a characteristic pattern of symptoms although most are unspecific. The slight difference between sexes in the median age of diagnosis was significantly increased in the age of death, with men being the group with the highest mortality and an earlier death.

Key messages

In the Valencian Region of Spain, men with Huntington Disease have a higher mortality rate and a lower median age at death (5.5 years earlier) than women. There is a pattern of symptoms which is characteristic of Huntington Disease, although most of them are unspecific.

Linking a European cohort of children born with congenital anomalies to vital statistics and mortality records: A EUROlinkCAT study

EUROCAT is a European network of population-based congenital anomaly (CA) registries. Twenty-one registries agreed to participate in the EUROlinkCAT study to determine if reliable information on the survival of children born with a major CA between 1995 and 2014 can be obtained through linkage to national vital statistics or mortality records. Live birth children with a CA could be linked using personal identifiers to either their national vital statistics (including birth records, death records, hospital records) or to mortality records only, depending on the data available within each region. In total, 18 of 21 registries with data on 192,862 children born with congenital anomalies participated in the study. One registry was unable to get ethical approval to participate and linkage was not possible for two registries due to local reasons. Eleven registries linked to vital statistics and seven registries linked to mortality records only; one of the latter only had identification numbers for 78% of cases, hence it was excluded from further analysis. For registries linking to vital statistics: six linked over 95% of their cases for all years and five were unable to link at least 85% of all live born CA children in the earlier years of the study. No estimate of linkage success could be calculated for registries linking to mortality records. Irrespective of linkage method, deaths that occurred during the first week of life were over three times less likely to be linked compared to deaths occurring after the first week of life. Linkage to vital statistics can provide accurate estimates of survival of children with CAs in some European countries. Bias arises when linkage is not successful, as early neonatal deaths were less likely to be linked. Linkage to mortality records only cannot be recommended, as linkage quality, and hence bias, cannot be assessed.

Congenital Anomalies and assisted conception in the Population-based registry from a Spanish Region

Background

The Congenital Anomalies (CA) population-based Registry of Valencian Region (RPAC-CV) has identified 12917 cases during 2007-2017, confirmed by clinical documentation. The Spanish Fertility Society (SEF) has identified a CA's prevalence per 10000 live births (LB) from assisted conception of 305.2 with a 95% confidence interval (CI) of 296.1-314.2 from 2013 to 2017.

Objective

to identify differences in sociodemographic and clinical characteristics between cases with CA according to the type of conception: natural (N) or assisted (A). To determine the CA's prevalence of LB in the RPAC-CV.

Methods

RPAC-CV cases since 2007 until 2017 were classified in N or A conception, and their sociodemographic and clinical characteristics were compared. Cases with no information about type of conception were excluded. The prevalence per 10000 LB with CI 95% in the RPAC-CV between 2013-2017 was calculated.

Results

Conception's information was available in 58.3% of the cases (90.4% N, 9.6% A). Differences were found in the following variables (values are shown by %N/%A) multiple pregnancy (6.5%/47.9%); birth before the 37th gestational week (24.5%/56.8%); weight at birth less than 2500 grams (24.6%/55.2%); dead before one week of age (4.4%/7.9%); mother older than 35 years (31.3%/64.2%). Statistically significant differences were found in the Nervous System CA group, being a higher proportion in A conception cases (12.5% (CI95%:9.8-15.2)) than in N (7.6% (CI95%:6.9-8.3)). The CA prevalence per 10000 LB in RPAC-CV was 194.1 (CI95%:188.3-199.9).

Conclusions

The CA's prevalence in the RPAC-CV was significantly lower compared to SEF's. Partially could be due to SEF includes minor CA and RPAC-CV not, although differences are overly high. Encourage the collection of the conception information in the clinical documentation will increase data quality in cases from assisted conception and allow having interesting information available for the development of health policies and research.

Key messages

CA’s prevalence, identified in a population-based registry from a Spanish region, was significantly lower than the one identified in assisted conception cases at national level for the same period. Analysing natural versus assisted conception, significant differences in cases’ characteristics have been identified in a CA’s population-based registry in Spain.

From ICD10 to ORPHAcodes: paving the way towards improved identification systems for rare diseases

Background

The International Classification of Diseases 10th revision (ICD10) and its clinical modification (ICD10CM) are commonly used for the identification of diseases occurrence worldwide. In Spain, diagnoses are coded with its Spanish version (ICD10ES) since 2016 regardless of the prevalence of diseases. Rare diseases (RDs) are scrambled among common diseases in ICD10 and its derivatives and many RDs dońt have a specific ICD10 code, delaying a proper identification. Orphanet developed a classification system specific for RDs called ORPHAcode. This study aims to characterize whether ICD10ES mapping to ORPHAcodes improves RDs identification and which kind of disorders would benefit the most.

Methods

95% of the disorder level ORPHAcodes indexed at Orphanet was mapped to codes from 20 ICD10ES chapters by comparing the descriptors associated in both classifications. ORPHAcodes were then clustered based on their assigned ICD10ES chapter and the redundancy of each individual ICD10ES code was calculated by counting the ORPHAcodes they mapped to. 3 groups were established: Group 1 (1 ORPHAcode per ICD10ES), Group 2 (between 2-49 ORPHAcodes per ICD10ES) and Group 3 (≥50 ORPHAcodes per ICD10ES).

Results

5588 ORPHAcodes were correlated to 1677 ICD10ES codes. 1051 were group 1, 3261 group 2 (615 ICD10ES) and 1276 group 3 (11 ICD10ES). Most of the Orphacodes correlated to “Q” (>40%), “G” (>14%) and “E” (>12%) chapters of ICD10ES. Regarding specificity, “G” and “Q” were also the only chapters including group 3 ORPHAcodes, while less than 10% of the ORPHAcodes linked to these chapters were in group 1.

Conclusions

New and improved ICD10ES codes are required because just 20% of all ORPHAcodes studied were into group 1. Especial care should be put on the two majoritarian chapters, “Q:Congenital Anomalies” and “G:Nervous System”, that show the lowest specificity for RDs. Complementary use of ORPHAcodes would improve the identification and registry of RDs either.

Funded: Project RD-CODE

Key messages

The lack of a specific chapter for Rare Diseases in the InternationaI Classification of Diseases hinders their identification and therefore their study. Direct mapping between ICD10 and ORPHAcodes or the use of ORPHAcodes for diagnoses codification of Rare Diseases would enable better detection and epidemiological analysis.

Validity of sources of information used for the identification of Wilson’s disease in the Registries

Background

Objective: to determine the sources of information used by the Regional Population-based Registries of Rare Diseases (RD) (RRD) for the identification of the Wilson’s Disease (WD) during the period 2010-2015, and to evaluate the validity of these sources.

Methods

A cross-sectional study was conducted involving 14 different Spanish Regions and the RD Research Institute. Possible cases with WD diagnosis included in RRD were identified with codes 275.1 in ICD9CM or E83.0 in ICD10 (unspecific codes referring to ’Disorders of copper metabolism’), and they were confirmed or not through a validation process in which clinical documentation was reviewed. Each Region sent their database to the coordinator (Valencian Region), which calculated the positive predictive value (PPV) for each source used individually and for the combination of two sources.

Results

995 records were identified and reviewed. 444 were confirmed, 475 were discarded and 76 were considered as possible. The PPV for all sources was 44.6%. The Hospital Discharge Database (CMBD) stands out as the main source of detection of possible cases with a PPV of 42.1%, followed by the Orphan Drugs Registry (ODR) with a higher PPV (80.8%) and by the Mortality Registry with a lower PPV (16.7%). The Clinical History of Primary Care (PC) obtained a VPP of 55.8%, but was only used in three Spanish Regions. The PPV for the combinations of two sources of information was 94.5% for the CMBD with the ODR, 91.5% for the ODR with PC and 73.9% for the CMBD with PC.

Conclusions

Although CMBD has been the most widely used source, its PPV is not the highest. However, the ODR is the source with the highest PPV. The introduction in 2016 in the CMBD of the Spanish version of the ICD10 which includes a specific code for the WD (E83.01) is expected to improve this value. Cases identified by both (CMBD and ODR) may be automatically validated due to the high PPV obtained.

Funding: Fundació Per Amor a l’Art and Obra Social “la Caixa”

Key messages

Wilson’s disease is one of the 10 Rare Diseases included in the Spanish Registry of Rare Diseases but the validity of sources of information hadn’t been studied. The introduction in 2016 in the Spanish Hospital Discharge Database of the Spanish version of the ICD10 will improve the validity of the sources of information used by the Registries of Rare Diseases.

Tetralogy of Fallot in infants less than one year old in the Valencia Region (Spain)

Background

Tetralogy of Fallot (TF) is a rare disease characterized by the presence of 4 congenital heart defects (CHD). Objective: to describe the temporal trend and distribution of the TF in the Valencia Region (VR), in less than one year old, during the period 2007-2016.

Methods

Live births, stillbirths and termination of pregnancy due to fetal anomaly (TOPFA) between 2007-2016 with TF (code Q21.3 of the ICD10-BPA) were selected from the Congenital Anomalies (CA) population-based Registry of VR. The cases were confirmed through the review of clinical documentation. The prevalence of 10000 births with 95% confidence intervals (95%CI) was calculated for the period and for each year, and a descriptive analysis of sociodemographic and clinical variables was made.

Results

146 cases were identified (45.2% male, 31.5% female and 23.3% unknown), 89.0% were simple pregnancies and 54.8% were diagnosed prenatally. The overall prevalence of TF was 3.0/10000 births (95%CI: 2.5-3.5), being 2015 the year with the highest prevalence (4.3/10000 births) and 2011 with the lowest (1.8/10000 births). These changes were mainly due to the increase and decrease in the number of TOPFA respectively. 74.7% were live births, 22.6% TOPFA and 2.7% stillbirths. The prevalence in live births was 2.2/10000 births (95%CI: 1.8-2.6) and in TOPFA it was 0.7/10000 births (95%CI: 0.4-0.9), identifying an increasing trend during the period in the last one. 11.0% of live births died during the first year of life. 45.9% of the cases had another CA associated with the TF, being CHD in 52.7% of cases. 66.4% of the mothers were over 30 years of age, being the most frequent those between 30-34 years (30.1%).

Conclusions

The prevalence obtained in the VR was lower than that of EUROCAT 3.5/10000 births (95%CI: 3.3-3.6) during the same period. EUROCAT has also identified the difference between the prevalence in live births (2.9 (95%CI: 2.8-3.0)) and TOPFA (0.5 (95%CI: 0.5-0.6)), and the increasing trend in the last one.

Key messages

The prevalence of Tetralogy of Fallot obtained in the VR was lower than that of EUROCAT (European network of population-based registries for the epidemiologic surveillance of congenital anomalies). EUROCAT has also identified the difference between the prevalence of Tetralogy of Fallot in live births and termination of pregnancy due to fetal anomaly, and the increasing trend in the last one.

[Temporal variation and geographical distribution: congenital heart defects in the Comunitat Valenciana]

OBJECTIVES

The objective of this study is to estimate the prevalence of congenital heart defects (CHD) in the Comunitat Valenciana (CV) in children less than one year old and identify whether there are temporal and geographic variations within this prevalence.

METHODS

The minimum basic data set from hospital discharge reports was used to select patients, who were born between 1999-2008, were less than one year old, and who lived in the CV with at least one hospital admission in which the primary diagnosis and/or any of the events were coded as CHD (codes 745-747 of the International Classification of Diseases 9th Revision Clinical Modification). The first hospital discharge report with CHD was selected, using the health card number to detect duplication. The prevalence and 95% confidence intervals were calculated, and the prevalence ratio (PR) and smoothed PR was obtained for each municipality to identify geographic patterns.

RESULTS

In the period 1999-2008 there were 6.377 patients younger than one year with some CHD, representing the 43.2% of cases of congenital anomalies. The prevalence was 134.3 per 10.000 live births (95% CI: 131.1-137.6). There was a significant increase in the prevalence, from 115.8 in the 1999-2003 period to 149.5 in the 2004-2008 period. A higher risk was identified in the north of the CV, and in some municipalities of the province of Alicante, in the south.

CONCLUSIONS

The observed increase in CHD agrees with the findings in other countries and it can be explained, at least in part, by improved diagnostic techniques. The geographic pattern identified requires a more detailed analysis that could explain the geographic variations found.

Analysis of the renal transplant waiting list in the País Valencià (Spain)

In this paper we analyse the renal transplant waiting list of the País Valencià in Spain, using Queueing theory. The customers of this queue are patients with end-stage renal failure waiting for a kidney transplant. We set up a simplified model to represent the flow of the customers through the system, and perform Bayesian inference to estimate parameters in the model. Finally, we consider several scenarios by tuning the estimations achieved and computationally simulate the behaviour of the queue under each one. The results indicate that the system could reach equilibrium at some point in the future and the model forecasts a slow decrease in the size of the waiting list in the short and middle term.

[Analysis of survival in dialysis: hemodialysis versus peritoneal dialysis and the significance of comorbidity]

To choose the best possible dialysis technique for those patients with end-stage renal disease continues to be a matter of debate. Even after putting aside the evident influence that economic and geographic factors as well as the health politics may have in the selection of the technique, different studies comparing survival between hemodialysis (HD) and peritoneal dialysis (PD) have shown contradictory results which could be explained by the differing methodological and statistical methods used together with the different influence assigned to the comorbidity found when starting the treatment, a situation that has increased the confusion about this topic. Based on this we performed a retrospective analysis with a follow-up time of seven years including all those patients who started dialytic treatment in our area, with a final number of 3.106 hemodialysis patients and 542 peritoneal dialysis patients. Those patients who were transferred to another treatment technique during the time of the study were excluded. Age higher than 70 years, cardiovascular disease, liver disease, diabetes mellitus and the presence of dyslipidemia were included as comorbidity factors. Peritoneal dialysis patients were younger than those treated by hemodialysis (54.53 vs 60.1 years), but suffered from higher cardiovascular comorbidity and were more often diabetic. The global survival was the same in both groups up to 32 months of treatment. Although no differences were found when comparing those patients without comorbidity factors, those with comorbidity had better survival on hemodialysis. Age higher than 70 years was the only comorbidity factor with statistically significant difference for a better survival in hemodialysis.

[Point processes as a tool for analyzing possible sources of contamination]

Point pattern analysis pattern comprises a series of techniques that enables the distribution of a series of events occurring in the vicinity of a particular region of a map to be studied. In epidemiology, this problem arises when a potential source of environmental contamination, possibly leading to cases of a specific disease, is investigated.The present study provides a brief description of point pattern analysis. The approach is illustrated through determination of the environmental source and study of the areas of greatest risk of incidence of an outbreak of legionella pneumonia that occurred between the middle of September and beginning of October in the city of Alcoi in Alicante (Spain).Point pattern analysis was able to confirm the environmental source of the outbreak and identify the areas of the city at greatest risk. This provided the justification for an exhaustive inspection of the installations generating aerosols after which, to date, the epidemics ceased.

[Incorporation of geostatistical methodology for influenza surveillance in a sentinel network]

OBJECTIVES

To evaluate geostatistical description of influenza data from the Valencian Sentinel Network (VSN) in Spain using the kringing method and to assess the possibility of incorporating this method into routine surveillance.

METHODS

We use influenza surveillance data on three influenza seasons (1997-1998, 1998-1999 and 1999-2000) from the VSN to construct a geocodified data matrix of the incidence of this disease. The geographic distribution was studied using the kringing method, which enables estimation of the incidence in a few strategically distributed points. Influenza isoincidence maps for each week were plotted. Cross validation was used to evaluate the method.

RESULTS

In most of the weeks, the values of reduced standard deviation and reduced mean were close to the optimal values (0 and 1, respectively). Out of range reduced standard deviation values were found in 12 of 20 weeks in the last season only. The estimation of rates in all three seasons showed coherence in spatial distribution and temporal evolution.

CONCLUSIONS

In most situations the results were acceptable. The method does not require extra computer resources or an excessive amount of time and requires only annual adaptation. Because it is easy to use, the technique is appropriate for routine use but the accuracy of estimations could be improved by increasing the complexity of the model.

[A morbidity information system based on school absenteeism]

We present a pilot experience about the introduction of a information system designed for the knowledge of infant morbidity (4-15 years) in a 13 school week period in a representative sample of 60 schools of the Valencian Community. We studied school absences that lasted three days or longer. Reports of teachers and parents were the source of information (100% response rate). Medical certification was also requested to the pediatricians and general practitioners of the area of the schools (12.74% response rate). To test the validity of this information system, absences caused by hepatitis were compared with the registry of Notifiable Diseases System (NDS) for the same period. We recorded 3,968 absences, with a cumulative incidence of 100.68 per 1,000 (C.I., alpha = .05, +/- 4.97) for females, and 119.4 (C.I., alpha = .05, +/- 18.36) for males. These differences were statistically significant. There was a concordance of 80.25% of the hepatitis cases between the registry of absenteeism and that of the NDS (chi 2 goodness of fit test = 3.16, p = .754). Although absences shorter than 3 days were not taken into account, the information system provided relevant and valid estimates of morbidity. Moreover, collaboration of teachers was considered very positive, which led us to use this health information system in five health areas of the Valencian Community.