Hypersensitivity vasculitis in adults: a benign disease usually limited to skin

OBJECTIVES

To examine the clinical spectrum of hypersensitivity vasculitis (HV) in an unselected population of adults and establish differences between patients with HV limited to the skin and those with systemic involvement.

METHODS

Retrospective study of adult patients (> 20 years) with biopsy-proven cutaneous leukocytoclastic vasculitis diagnosed as having HV, who were seen at the single hospital serving a well defined population between 1984 and 1998. Patients were classified as having HV according to the criteria of Michel et al. (9). To examine outcome and relapses of the disease only those patients with a follow-up of at least 1 year were included in this study.

RESULTS

64 patients with a mean follow-up of 4.9 +/- 3.5 (range: 1.1-13.6) years were studied. Ten (15.6%) had visceral involvement (3 gastrointestinal and 7 renal manifestations) during the course of the disease. The remaining patients had a leukocytoclastic vasculitis limited to the skin. When the study was concluded persistent hematuria and proteinuria was only observed in 1 patient and none developed renal insufficiency. Patients with a history of drug treatment and elevated ESR had more systemic complications but the difference was not statistically significant. The outcome was excellent in both patients with HV limited to the skin and in those with systemic complications during the course of the disease.

CONCLUSIONS

In unselected adults HV is generally a benign disease confined exclusively to the skin. In those patients with systemic manifestations, visceral involvement is generally mild and transient.

Epidemiology of surgical-site infections diagnosed after hospital discharge: a prospective cohort study

OBJECTIVE

To study postoperative infections in hospital and after discharge, and to identify the risk factors for such infections.

DESIGN

Prospective cohort study, with telephone follow-up for 1 month after hospital discharge.

SETTING

The general surgery service of a tertiary hospital in Spain.

MAIN OUTCOME MEASURE

In-hospital and postdischarge surgical-site infection (SSI), always confirmed by a physician.

RESULTS

Of the 1,506 patients initially enrolled, 29 died during hospital stay, and 33 were lost to postdischarge follow-up. An SSI was identified prior to discharge in 123 patients and after discharge in 103. For several variables (age, serum albumin, glycemia, lengths of preoperative and postoperative hospital stay, etc), there were no differences between patients with postdischarge SSI and noninfected patients; however, there were differences detected between patients with postdischarge SSI and in-hospital SSI, as well as between patients with in-hospital SSI and noninfected patients. The analysis of risk factors showed that most predictors for in-hospital SSI did not behave in the same manner for postdischarge SSI. Stepwise logistic regression only identified chemoprophylaxis, age (advanced age was a preventive factor), and body mass index as independent risk factors for postdischarge SSI. Differences in risk factors between in-hospital and post-discharge SSIs remained even after controlling for time from operation to diagnosis.

CONCLUSIONS

Most predictors of in-hospital SSI were not predictors of postdischarge SSI.

Rheumatic manifestations of infective endocarditis in non-addicts. A 12-year study

Infective endocarditis (IE) is due to a microbial infection of the heart valves or of the endocardium in close proximity to either congenital or acquired cardiac defects. This infection is associated with a high risk of complications. Rheumatic manifestations are known to be frequent complications of IE. Controversy, however, frequently exists about the actual incidence of these complications. This may be due to the small number of series describing the frequency and type of rheumatic manifestations, the absence of uniform criteria used for the diagnosis of IE, and the fact that some studies on rheumatic manifestations in IE have been described from tertiary referral centers, which implicates associated problems of referral bias and uncertainty of denominator population. To investigate further the incidence, clinical spectrum, and outcome of patients with IE and rheumatic manifestations, we examined the features of patients diagnosed with clinically definite IE according to the Duke classification criteria at the single reference hospital for a defined population in northwestern Spain during a 12-year period. Between 1987 and 1998, 100 consecutive patients had 110 episodes of clinically definite IE. Rheumatic manifestations were observed in 46 of the 110 episodes (41.8%). As in other western countries, they occurred more commonly in men aged in their 50s. The most frequent valve involved was the aortic (43.5%) followed by the mitral valve (30.4%). Myalgia was a frequent symptom. Peripheral arthritis, generally as monoarthritis, was clinically evident in 15 cases (13.6%), and sacroiliitis in 1 patient. Low back pain was described in 14 cases (12.7%). Septic discitis was observed in 2 cases, and biopsy-proved cutaneous leukocytoclastic vasculitis was found in 4 cases. Other conditions such as trochanteric bursitis and polymyalgia were observed in 2 and 1 case, respectively. Apart from a significantly higher frequency of hematuria and a trend to lower serum complement levels in patients with rheumatic complications, no differences in clinical features, laboratory tests, or microbiologic blood culture results were found between cases with IE with or without rheumatic manifestations. Also, although patients with rheumatic manifestations had more embolic complications, the inhospital mortality rate in patients with rheumatic manifestations was not significantly different from that of the rest of the patients. The present study supports the claim that rheumatic complications are frequent in patients with clinically definite IE from southern Europe. The presence of musculoskeletal or vasculitic manifestations may be of some help, as warning signs, for the recognition of patients with severe disease who require rapid diagnosis and therapy.

[Population attributable fraction: estimation and interpretation]

The goal of this paper is to revise the concept, estimation methods, and interpretations of the population attributable fraction. From the usual formula of the population attributable fraction: (Ip ­ I₀) / Ip, where Ip is the cumulative incidence in the overall population, and I₀ is the cumulative incidence in the non-exposed group, other formulae are presented for use in exposures with more than two levels, and in the presence of confounding factors. Differences in estimation methods between cohort and case-control studies are discussed, and equations to estimate confidence intervals are displayed. Finally, some interpretations -­including the concepts of «etiologic case» and «case in excess», suggested by Greenland and Robbins-­, and some habitual errors are discussed.

The butyrylcholinesterase K variant is a protective factor for sporadic Alzheimer's disease in women

INTRODUCTION

Recent reports indicate that the K variant of the butyrylcholinesterase (BCHE) gene may act in synergism with the epsilon4 allele of apolipoprotein E (APOE) to increase the risk of Alzheimer's disease (AD), but this is controversial.

MATERIAL AND METHODS

We genotyped for the BCHE-K and APOE epsilon4 alleles in a sample of 249 AD patients and 250 controls derived from the same region in a Spanish population.

RESULTS

A protective effect of the K variant of BCHE with an odds ratio of 0.41 (95% confidence interval 0.19-0.86, P=0.02) was observed among non-APOE epsilon4 carriers, but it was limited to women.

CONCLUSION

Our study is the first to demonstrate that lower susceptibility to AD determined by the K variant of BCHE is dependent on gender.

Competing risks in absence of independence: impact of AIDS on liver function failure mortality, and lung cancer on ischemic heart disease mortality

The increase in lung cancer (LC) mortality can produce a decrease in mortality from other causes, including ischemic heart disease (IHD). This problem (called the competing risks problem) has been addressed usually assuming independence between the competing causes of death. Our purpose is to show that assuming dependence of causes of death allows obtaining a better estimation of cumulative mortality. We use a clinical epidemiological example on the impact of AIDS in liver function failure in a cohort of drug users. The competing effect under dependence is 47% higher than under independence. This result is compared with a population-based example on LC and IHD mortalities in Spanish people in 1992. LC and IHD share tobacco smoking as a common risk factor, so independence cannot be assumed. Under the independence assumption, both life expectancy and number of deaths from IHD are underestimated. The difference is small compared to the model computed under dependence and it occurs mainly in the elderly (0.3% more deaths in people aged 70 and over).

[Comparison of 2 methods for calculating uncertainty in laboratory analysis]

OBJECTIVE

To compare two methods in the estimation of the uncertainty in laboratory quality control.

METHODS

A computerized simulation is performed to compare the delta method (suggested by the International Organization for Standardization and the Entidad Nacional de Acreditación) and a bootstrap-based method. The simulation includes several situations with different environmental conditions and different relationships between the analyzed variables.

RESULTS

The mean in the coverage obtained by the estimated confidence intervals is higher and closer to the nominal using the bootstrap than using the delta method. The most important differences are observed in the coverage percent distribution: while using the bootstrap, a great number of simulations obtain coverage near the nominal of 95%; using the delta method the coverage are more dispersed, including coverage of 100% in some occasions and lesser than 80% in others. The bootstrap offers very similar results under different conditions, including in the presence of unknown and unmeasured variables or when the analyzed variables are correlated. The delta method shows poorer results in both situations.

CONCLUSION

The uncertainty in the laboratory quality control can be estimated more accurately with bootstrapping than with the delta method.

[Role of primary care teams in hospitalization of children under 2 years of age?]

OBJECTIVE

To determine whether the structure of primary care teams on carrying out the healthy child health programme leads to a drop in the risk of admission to hospital of children under two, in comparison with the traditional clinic or out-clinic health system.

DESIGN

Case-reference epidemiological study.

CASES

40% of the children under 24 months admitted to paediatric or neonate floors of the Marqués de Valdecilla University Hospital. Reference: 15% of the recently born children alive in this hospital. Information was gathered through face-to-face interview and by examining health cards. The study ran from April 1995 to May 1996.

RESULTS

Children under two monitored habitually by a doctor belonging to a primary care team showed a drop in risk of hospital admission for all clinical diagnoses of 0.57 (95% CI, 0.35-0.93), after adjustment due to various confusion factors such as maternal education, social class, ethnic background, mother's age, mother's tobacco consumption, natural breast-feeding at birth, admission at birth. There was a drop of risk of hospital admission for high temperature without apparent cause in those children monitored habitually by a team doctor (adjusted RR = 0.41; 95% CI, 0.19-0.90).

CONCLUSIONS

The advantages of the paediatric health care reform with the structuring of the primary care teams and the accompanying activities performed lead to a drop in the risk of hospital admission of those children under two years old who are habitually monitored by a doctor belonging to a primary care team.

[Pre and perioperative factors determining early in-hospital mortality in patients over 75 years of age undergoing cardiac surgery]

INTRODUCTION AND OBJECTIVES

To know the in-hospital morbidity and mortality and the related factors in patients over 75 years old undergoing cardiac surgery.

PATIENTS AND METHODS

A retrospective analysis was carried out in 252 out of 2043 consecutive patients (129 female, 123 male) over 75 years of age (mean age 77.8 years; range 75 to 89 years) undergoing open heart surgery from january 1, 1994 to november 30, 1997. Isolated aortic valve replacement was performed in 128 patients, 78 underwent isolated coronary artery bypass grafting and 46 combined surgery. Preoperative determinants of morbidity and mortality were analyzed.

RESULTS

The overall hospital mortality was 15.1%, 13.2% in the aortic group, 12.8% in the coronary group and 23.9% in the combined surgery group. The overall morbidity rate was 38.6% and 25.8%, 34.2% in the aortic and coronary groups, respectively. Preoperative risk factors were prior surgery (p < 0.0004) and emergency operation (p < 0.04). In aortic valve replacement, NYHA class IV (p < 0.05), prior operation (p < 0. 01) and emergency surgery (p < 0.01) were determinant. Perioperative factors of early mortality were: prolonged cross-clamping > 60 min (p < 0.02), cardiopulmonary bypass time > 90 min (p < 0.002), need for inotropic drugs (p < 0.005) and postoperative complications (p < 0.00001). Mean postoperative length of hospital stay was 12.8 +/- 8. 5 days.

CONCLUSIONS

Despite the greater rate of early morbimortality in patients over 75 years of age, cardiac surgery may be performed avoiding emergency surgery, functional grade IV and prolonged length of surgery.

Epidemiological differences between sepsis syndrome with bacteremia and culture-negative sepsis

OBJECTIVE

To explore the association of putative disease markers and potential risk factors with the nosocomial sepsis syndrome.

DESIGN

Prospective case-control study matched for gender, age, and length of preinfection hospital stay.

SETTING

1,200-bed tertiary-care center in Spain.

PATIENTS

Cases were selected using the sepsis syndrome criteria of the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference and were divided into three groups: sepsis with bacteremia (109 cases), sepsis with positive culture other than blood (122 cases), and sepsis with negative culture (115 cases without documented infection but with sepsis syndrome, clinically suspected infection, and empirical antibiotic treatment). Controls were randomly selected from the daily list of inpatients. Data were collected prospectively. Crude and multiple-risk-factor-adjusted odds ratios and their 95% confidence intervals were computed using conditional logistic regression analysis.

RESULTS

Presence of coma in the 48 hours before sepsis, intensive care unit (ICU) stay, and decreased serum albumin levels at admission were common epidemiological markers identified for the three groups of cases. Having a central venous catheter was the main healthcare-related risk factor for bacteremia. ICU stay and nasogastric tube were the main risk factors for sepsis with positive culture other than blood. Coma within 48 hours before sepsis and the need of intensive care were the only two markers identified for culture-negative sepsis.

CONCLUSION

Culture-negative sepsis does not behave like culture-positive sepsis, and this may imply that implementation of preventive measures to decrease the risk of bacteremia may not decrease the risk of sepsis syndrome.

[Influence of parental smoking on pediatric hospitalization for respiratory illness among children aged less than 2 years]

AIM

To determine whether parental smoking increased the risk of hospitalization among children aged less than 2 years.

DESIGN

Case-reference study conducted from April 1995-May 1996. The group of cases was composed of 40% of all the children aged 2 years or less years admitted to our hospital (n=392). The reference population was composed of 15% of the live newborns in the same the hospital (n=493). The information was obtained by face-to-face interview after delivery in both populations and by telephone interview or postal survey and was completed in the reference population one year after delivery.

RESULTS

Maternal smoking increased the risk of hospitalization for lower respiratory illness (adjusted RR - 1.79; 95% CI = 1.03-3.11). Moreover, the risk of hospitalization for upper or lower respiratory illness, lower respiratory illness and bronchiolitis was increased when the mother smoked more than 19 cigarettes per day. The results were adjusted for confounding factors such as prenatal age, ethnic group, maternal education, social class, breastfeeding and hospitalization of the newborn. Parental smoking, specifically maternal smoking, affects children's health, increasing the risk of hospitalization for respiratory illness in the first 2 years of life.

Visual manifestations of giant cell arteritis. Trends and clinical spectrum in 161 patients

Giant cell (temporal) arteritis (GCA) is the most common systemic vasculitis in Western countries. It involves large and medium-sized vessels with predisposition to the cranial arteries in the elderly. Cranial ischemic complications, in particular permanent visual loss, constitute the most feared aspects of this vasculitis. Although the use of corticosteroids and a higher physician awareness may have contributed to a decrease in the frequency of severe ischemic complications, permanent visual loss is still present in 7%-14% of patients. To investigate further the incidence, trends, and clinical spectrum of visual manifestations in patients with GCA, we examined the features of patients with biopsy-proven GCA diagnosed at the single reference hospital for a defined population in northwestern Spain during an 18-year period. Predictive factors for the development of any visual manifestation, not only permanent visual loss, were also examined. Between 1981 and 1998, 161 patients were diagnosed with biopsy-proven GCA. Visual ischemic complications were observed in 42 (26.1%), and irreversible blindness, mainly due to anterior ischemic optic neuropathy and frequently preceded by amaurosis fugax, was found in 24 (14.9%). Despite a progressive increase in the number of new cases diagnosed, there was not a significant change in the proportion of patients with visual manifestations during the study period (p = 0.37). Patients with visual ischemic complications had lower clinical and laboratory biologic markers of inflammation. Indeed, during the last years of the study, anemia was associated with a very low risk of visual complications. Also, HLA-DRB1*04-positive patients had visual manifestations more commonly. Patients with other ischemic complications developed irreversible blindness more frequently. The best predictors of any visual complication were HLA-DRB1*04 phenotype (odds ratio [OR] 7.47) and the absence of anemia at the time of admission (OR for patients with anemia = 0.07). The best predictors of irreversible blindness (permanent visual loss) were amaurosis fugax (OR 12.63) and cerebrovascular accidents (OR 26.51). The present study supports the claim that ocular ischemic complications are still frequent in biopsy-proven GCA patients from southern Europe. The presence of other ischemic complications constitutes an alarm for the development of irreversible blindness. In contrast, a higher inflammatory response may be a protective factor against the development of cranial ischemic events.

Polymorphism at codon 129 of the prion protein gene is not associated with sporadic AD

An association between cognitive performance in elderly people and variability in the codon 129 of the prion protein gene (PRNP) has been recently described. The authors analyzed this polymorphism in 278 sporadic AD patients and 268 cognitively normal control subjects. Analyses stratifying by APOE genotype, age, and gender failed to reveal any association between homozygosity for the 129 PRNP methionine or valine alleles and AD.

Detection of Epstein-Barr virus DNA in a patient with Kimura's disease

An 80-year-old man, with a past medical history of senile dementia, presented with a 6-month history of a solitary, gradually enlarging tumor, located on his chin. A squamous cell carcinoma had been surgically excised 30 years previously in the same location. Physical examination revealed an erythematous, well-defined plaque of 3 cm in diameter, located on the chin (Fig. 1). The submandibular lymph nodes were enlarged. Squamous cell carcinoma and primary cutaneous lymphoma were considered. Relevant laboratory findings were as follows: white blood cell count, 5.600/microL; eosinophils, 1000/microL; gammaglobulin, 2.4 g/dL; lactate dehydrogenase, 343 IU/L; and immunoglobulin G (IgG) antibodies to Epstein-Barr virus (EBV) positive (at 1 : 128 serum dilution), with negative IgM. Skin and lymph node biopsies were performed. Histopathologic study of the cutaneous specimen revealed a heavy lymphoid infiltrate with numerous lymphoid follicles, with prominent germinal centers involving the subcutaneous fat as well as the deep dermis and muscular fascia. Some germinal centers showed folliculolysis. The lymphoid follicles were surrounded by fibrous tissue. The interfollicular infiltrate was rich in plasma cells and eosinophils that formed scattered eosinophilic microabscesses. Thin-walled vessels were numerous and prominent, but with no epithelioid or vacuolated endothelial cells (Fig. 2). Histopathology of a lymph node biopsy specimen showed reactive lymphoid follicle hyperplasia, with prominent eosinophilic infiltrates in both follicular and interfollicular areas. Eosinophilic deposits and polykaryocytes of Warthin-Finkeldey type were seen in the germinal centers. The paracortical area showed vascular proliferation. Polymerase chain reaction (PCR) for the detection of specific sequences of EBV from routinely processed paraffin-embedded material was carried out under the conditions and with the same set of primers as described previously in detail (Tenorio A, Echevarría JE, Casas E et al. J Virol Methods 1993; 44: 261-269). DNA samples were confirmed to be amplifiable with PCR primers specific for a conserved region of the human beta-globin gene. Every sample was tested at least twice for EBV DNA and beta-globin gene. One sample from one skin lesion of the patient, with confirmed diagnosis of Kimura's disease, and 10 samples from normal skin biopsies retrospectively collected from other patients in archival files of our department were tested. Only the patient's specimen tested positive to EBV. The amplified product of EBV was analyzed using DNA sequencing and confirmed the results obtained. The patient received radiotherapy at doses of 35 Gy. Nevertheless, the tumor enlarged to reach twofold its original size 1 month later. Due to the physical status of the patient, no further treatments were considered, but the disease remained stable over the following 3 years.

Analysis of risk factors for nosocomial sepsis in surgical patients

BACKGROUND

This study aimed to identify patients at high risk for developing sepsis following surgery according to criteria determined by the American College of Chest Physicians and the Society of Critical Care Medicine Consensus Conference on sepsis.

METHODS

A prospective case-control study was performed in surgical patients in a tertiary care centre over 1 year. Patients were identified by a daily prospective surveillance. Controls were selected randomly from the daily list of surgical inpatients. Data were collected prospectively. Crude and adjusted odds ratios (ORs) and their 95 per cent confidence intervals were computed using logistic regression analysis.

RESULTS

During follow-up, 99 cases and 99 controls were identified. The main risk factors for sepsis found in the multivariate analysis were coma within 48 h before sepsis (OR 13.5, 95 per cent confidence interval 3.6-50.8), low serum albumin level at admission (OR 15.8, 5.4-46.4), two or more intrinsic co-morbidities (OR 11.8, 2.8-49.4) and parenteral nutrition (OR 5.1, 1.5-17.1). Emergency surgery (OR 3.0, 1.4-6.4), abdominal surgery (OR 2.6, 1.0-6.8) and number of surgical interventions (OR 2.5, 1. 1-6.1) were the variables related to surgery that significantly increased the risk of sepsis. Both the study on the Efficacy of Nosocomial Infection Control (SENIC) and the National Nosocomial Infections Surveillance indices showed a statistically significant trend with sepsis.

CONCLUSION

Patient-related factors appear to represent the greatest risk for developing postoperative nosocomial sepsis, rather than factors associated with the surgery.

A comparison of several procedures to estimate the confidence interval for attributable risk in case-control studies

The estimation of a confidence interval for attributable risk from the logistic model based on data from case-control studies is a problem for which an accepted solution is lacking. Two methods, one based on the delta method and one bootstrap on the population base, have been described but their accuracy has not been compared. We present two other methods, one based on a jack-knife approach and the other using a bootstrap on two samples (cases and controls). The four methods are compared in a simulation study. The four methods are also applied to a case-control study on risk factors for preterm delivery; the confidence intervals are obtained assuming normality and by logarithmic transformation. When attributable risk is not smooth (for example, when exposure prevalence is low) both the jack-knife and the delta method tend to fail. If attributable risk is close to zero or one, normality cannot be assumed and log-transformed confidence intervals must be used. Finally, the extension to matched studies is analysed using a case-control study on risk factors of cutaneous malignant melanoma. In this situation, the population-based bootstrap is not available.

Identification of weak interfaces in composites using transmission electron microscopy

A new experimental technique was developed to identify crack paths with a resolution of nanometres in fibre-reinforced composites. Cracks were introduced through Vickers indentations on one side of the sample prior to starting the thinning process. Indentations were placed close to the fibres in order to get enough cracks at the fibre/matrix interface in the electron-transparent region of the thinned sample. The technique was used in a Nicalon-fibre Al2O3 matrix composite prior to and after a heat treatment at 1200 degrees C for 1 h. The analysis of the crack paths allowed the identification of the weakest interface in each condition.

[The measurement of inequalities in age of death: calculating the Gini Index based on mortality tables]

The Gini index has been used to gauge the concentration of different variables, including income, the mortality distribution and the spread of physicians. The use of the Gini index for gauging the inequalities in the age of death based on actuarial mortality data. For this purpose, the 1990 age and gender-related mortality figures for each Autonomous Community were used. The inequalities in the number of years lived are greater among males than among females throughout all of the Autonomous Communities. The Communities showing the longest life expectancies are those which have also been revealed to involved the least degree of inequality in the number of years lived, which therefore makes in possible to pinpoint health-care priorities in some cases. The Gini index can be applied to age-related mortality for gauging the degree of inequality in the age of death and to pinpoint age groups on which to place priority with regard to health-care measures.

Effect of SiC reinforcement on the deformation and fracture micromechanisms of Al-Li alloys

The effect of SiC reinforcement on the microstructure of a naturally aged 8090 Al alloy as well as on the deformation and fracture micromechanisms was investigated. To this end, the microstructural characteristics (grain and reinforcement morphology, precipitate structure) were determined in the unreinforced alloy and in the composite reinforced with 15 vol.% SiC particles. The materials were tested under monotonic tension and fully reversed cyclic deformation and then carefully analysed through scanning and transmission electron microscopy to find the dominant deformation and failure processes for each material and loading condition. It was found that the dispersion of the SiC particles restrained the formation of elongated grains during extrusion and inhibited the precipitation of Al3Li. As a result, the plastic deformation in the composite was homogeneous, while strain localization in slip bands was observed in the unreinforced alloy specimens tested in tension and in fatigue. The unreinforced alloy failed by transgranular shear along the slip bands during monotonic deformation, whereas fracture was initiated by grain boundary delamination, promoted by the stress concentrations induced by the slip bands, during cyclic deformation. The fracture of the composite was precipitated by the progressive fracture of the SiC reinforcements during monotonic and cyclic deformation.

[Mortality due to multiple sclerosis in Spain, 1951-1992]

FOUNDATIONS: In this work, multiple sclerosis mortality trend in Spain from 1951 to 1992 is displayed. The purpose is to identify the pattern of age-adjusted mortality evolution and to measure the effect of environmental factors.

METHODS

Multiple sclerosis mortality is standardized by age using the world standard population. In each year from 1951 to 1992, age-specific mortality rates are transversely fitted to the Gompertz law. The Longitudinal Gompertzian analysis is applied to the obtained coefficients to quantify the effects of competing risks and environmental factors.

RESULTS

Multiple sclerosis age-adjusted mortality increased from 1951 to 1968; a step-down is produced in 1969 (coinciding with change from 7th to 8th revision of the International Classification of Diseases) and a stability from 1970 on. Multiple sclerosis in Spain is a Gompertzian disease. Adjusting mortality for R0 (which in the Gompertz function represents the addition of the environmental factors acting in a point near the beginning of the life and the competing risks of death) the result was almost constant throughout the whole analyzed period.

CONCLUSIONS

It is suggested that multiple sclerosis mortality trend in Spain is due to changes in some environmental factor acting early and in a point; on the other hand, diet or other environmental factors acting for long time or genetic factors have and little or no influence in this trend.