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Ake Svensson

Publications and source records attributed to Ake Svensson.

At least 19 recordsLinked to original sources
PubMed2006

A note on generation times in epidemic models.

The time between the infection of a primary case and one of its secondary cases is called a generation time. The distribution (and mean) of the generation times is derived for a rather general class of epidemic models. The relation to assumptions on distributions of latency times and infectious times or more generally on random time varying infectiousness, is investigated. Serial times, defined as the times between occurrence of observable events in the progress of an infectious disease (e.g., the onset of clinical symptoms), are also considered.

Algorithms↗
PubMed2006

Occurrence of invasive pneumococcal disease and number of excess cases due to influenza.

BACKGROUND: Influenza is characterized by seasonal outbreaks, often with a high rate of morbidity and mortality. It is also known to be a cause of significant amount secondary bacterial infections. Streptococcus pneumoniae is the main pathogen causing secondary bacterial pneumonia after influenza and subsequently, influenza could participate in acquiring Invasive Pneumococcal Disease (IPD). METHODS: In this study, we aim to investigate the relation between influenza and IPD by estimating the yearly excess of IPD cases due to influenza. For this purpose, we use influenza periods as an indicator for influenza activity as a risk factor in subsequent analysis. The statistical modeling has been made in two modes. First, we constructed two negative binomial regression models. For each model, we estimated the contribution of influenza in the models, and calculated number of excess number of IPD cases. Also, for each model, we investigated several lag time periods between influenza and IPD. Secondly, we constructed an "influenza free" baseline, and calculated differences in IPD data (observed cases) and baseline (expected cases), in order to estimate a yearly additional number of IPD cases due to influenza. Both modes were calculated using zero to four weeks lag time. RESULTS: The analysis shows a yearly increase of 72-118 IPD cases due to influenza, which corresponds to 6-10% per year or 12-20% per influenza season. Also, a lag time of one to three weeks appears to be of significant importance in the relation between IPD and influenza. CONCLUSION: This epidemiological study confirms the association between influenza and IPD. Furthermore, negative binomial regression models can be used to calculate number of excess cases of IPD, related to influenza.

Disease Susceptibility↗
PubMed2006

Contact allergy to herbal teas derived from Asteraceae plants.

Contact allergy to herbal teas derived from the Asteraceae plant family was investigated in patients allergic to sesquiterpene lactones (SLs). 20 patients with a known contact allergy to SLs were recalled and patch tested with aqueous extracts of 8 different herbal teas based on Asteraceae plants as well as with parthenolide and other SLs. In 18 of 20 patients with SL allergy, there were positive test reactions to the Asteraceae teas, mainly to those based on German chamomile, dandelion and wormwood. Among the SLs, parthenolide was the most frequent co-reactor. Obviously, most patients with a contact allergy to SLs are allergic to commercial teas derived from the Asteraceae plant family as well.

Adult↗
PubMed2006

Is the question 'Have you had childhood eczema?' useful for assessing childhood atopic eczema in adult population surveys?

Atopic eczema (AE) is a major risk factor for hand eczema. In Scandinavian population-based studies, the occurrence of AE in childhood has often been assessed by the question 'Have you had childhood eczema?' In the present study, this question was validated. A questionnaire was sent to 600 cases with AE and 600 controls without eczema or allergic disease, identified in school medical records from the 1960s. The response rate was 70.5%, and the mean age of the respondents was 36.7 years. The specificity of the question was 70.7% and the sensitivity 89.9%. The sensitivity was higher and the specificity lower in a subgroup with current hand eczema compared with a group without hand eczema. The results showed that the question overestimated the prevalence of AE in childhood by a factor of 1.6. When used for risk assessment, the question provided a better estimate of the risk of current hand eczema as compared with the lifetime risk of hand eczema. In conclusion, the validated question overestimated prevalence of childhood AE and may overestimate AE as a risk factor for hand eczema in adult population surveys.

Adolescent↗
PubMed2005

Mortality following Campylobacter infection: a registry-based linkage study.

BACKGROUND: Campylobacteriosis is one of the most commonly identified causes of bacterial diarrheal disease and a common cause of gastroenteritis in travellers from developed nations. Despite the widespread occurrence, there is little information on Campylobacter mortality. METHODS: Mortality among a cohort of Campylobacter cases were compared with the general population 0-1, 1-3, 3-12 and more than 12 month after the onset of the illness. The cases were sub-grouped according to if they had been infected domestically or abroad. RESULTS: The standardized mortality ratio for cases infected domestically was 2.9 (95% CI: 1.9-4.0) within the first month following the illness. The risk then gradually diminished and approached 1.0 after one year or more have passed since the illness. This initial excess risk was not attributable to any particular age group (such as the oldest). In contrast, for those infected abroad, a lower standardized mortality ratio 0.3 (95% CI: 0.04-0.8) was shown for the first month after diagnosis compared to what would be expected in the general population. CONCLUSION: Infection with Campylobacter is associated with an increased short-term risk of death among those who were infected domestically. On the contrary, for those infected abroad a lower than expected risk of death was evident. We suggest that the explanation behind this is a "healthy traveler effect" among imported cases, and effects of a more frail than average population among domestic cases.

Adolescent↗
PubMed2005

Does long-lasting hand dermatosis have an influence on everyday living among teenagers?

The purpose of this longitudinal study was to examine a cohort of secondary school pupils, aged 16-19 years (47 females and 18 males) with a 1-year prevalence of hand dermatosis. The study deals with the pupils' history of atopy, self-reported symptoms, exacerbating factors, protection habits, choice of education programme, self-rated health and impact on everyday life. The results showed that 61.5% of the pupils had a history of atopic dermatitis; 78% did not use protective gloves. Females reported use of corticosteroids more often than males. In all, 60% had not been given information at school about future occupational risks, when choosing education. The cohort changed education programme significantly more often than pupils reporting not having hand dermatosis. However, the cohort estimated their health as being as good as that of adolescents in the general population. The neglect of risks in choosing a future profession may cause not only suffering for the individual, but also costs for society.

Activities of Daily Living↗
PubMed2005

The occurrence of atopic dermatitis in Greenland.

Until recently there was no information available on the prevalence of atopic dermatitis in Greenland. Our objective was to determine the prevalence of atopic dermatitis in younger schoolchildren in Greenland. In the autumn of 2000 we used our previously elaborated questionnaire in a cross-sectional study of 954 schoolchildren aged 7-8 years, who lived in five Greenlandic towns. The findings were compared to data on atopic dermatitis from Denmark. The response rate was 65% (622). The lifetime prevalence of atopic dermatitis was calculated to be 14.0% (95% confidence interval 11.3-16.7) using our standard score criteria with an absolute lower limit estimate of 4.5%. Taking the response rate of 65% into consideration this study indicates that in 2000 the lifetime prevalence of atopic dermatitis among younger schoolchildren in Greenland was in the range of 10-15%.

Child↗
PubMed2005

Prevalence of hand eczema in an adult Swedish population and the relationship to risk occupation and smoking.

Using a postal questionnaire the prevalence of hand eczema was determined in a general population of 11,798 individuals aged 20-77 years who were randomly drawn from the population records. The response rate was 78.1%. One-year prevalence of hand eczema among women varied between 1.9% and 10.8%, with the highest figure among those aged 30-39 years. The corresponding figures for men were 2.3% and 5.6%, with the highest figure among those aged 20-29 years. Lifetime prevalence varied between 5.7% and 16.7% among women and between 5.2% and 9.5% among men. Using multiple logistic regression analysis female sex (OR=1.91, 95% CI 1.47-2.47) and smoking (OR=1.35, 95% CI 1.04-1.75) were independent risk factors for reporting 1-year prevalence of hand eczema, whereas age (OR=0.99, 95% CI 0.97-0.99) was inversely related to the 1-year prevalence of hand eczema. Aggregated risk occupation or categorized occupation such as medical and nursing work, production or service were not significantly associated with 1-year prevalence of hand eczema.

Adolescent↗
PubMed2005

Risk factors for domestic sporadic campylobacteriosis among young children in Sweden.

A case-control study was conducted in Sweden to study risk factors for domestically acquired Campylobacter jejuni/coli infections among children aged less than 6 y. A total of 126 cases, reported to the national surveillance system were recruited over 1 y. Controls, selected from the population register, were matched to the cases by age, gender, place of residence and time of infection of the case. Information was gathered by posted questionnaires. Two separate conditional regression models were developed including and excluding 'protective' factors. Two of the factors significantly associated with Campylobacter infection were water-related: having a well in the household (OR=2.6) and drinking water from a lake/river (OR=7.4; 6.0). Other exposures associated with increased risk were: having a dog (OR=8.4; 3.8) and eating grilled meat (OR=5.5; 2.1). Drinking unpasteurized milk was borderline significant in 1 model (OR=3.7). Eating sausage was protective (OR=0.05). Eating chicken was not a significant risk. Exposures such as eating grilled meat and drinking water from a lake or a river were more common in the warm months, a factor that may partly explain the observed seasonality. The authors suggest that differences between risk factors across studies may reflect geographical and age-specific differences in the sources of infection.

Adolescent↗
PubMed2005

Migration and smoking: an epidemiological study of Finnish twins in Sweden.

BACKGROUND: Male migrants from Finland to Sweden have been found to have a reduced risk of coronary heart disease after several years in Sweden. Changes in smoking habits may contribute to this reduced risk. AIMS: A study was undertaken to compare smoking habits in Finnish migrants to Sweden and subjects always living in Finland and to analyse whether the migration may have influenced smoking. METHODS: The study population consisted of same-sex twin pairs born in Finland younger than 76 years with at least one twin that had migrated to Sweden (n = 1,083 pairs). Smoking habits obtained by mailed questionnaire were compared in migration-discordant twin pairs to take into account early childhood and genetic factors. RESULTS: Immigrants and returnees with a history of smoking had predominantly started to smoke before the migration. Among women, immigrants to Sweden smoked more than never migrants in Finland, odds ratio (OR) 2.1 for current smokers (95% confidence interval CI 1.4-3.3) but this difference was already present before migration. In men there were essentially no differences in smoking prevalence between immigrants and never migrants but heavy smoking was less common among immigrants than among never migrant smokers, OR 0.5 (95% CI 0.2-0.9) and migration was associated with a greater propensity to cease smoking. CONCLUSIONS: Migration from Finland to Sweden does not seem to have had a strong influence on smoking among migrants. A favourable trend in smoking habits after migration may in part have contributed to reduced mortality and incidence of coronary heart disease in male Finnish migrants after several years in Sweden.

Adult↗
PubMed2005

Influence of childhood atopic dermatitis on future worklife.

OBJECTIVES: The purpose of this study was to perform a population-based follow-up of people with childhood atopic dermatitis with respect to the possible influence on their worklife. METHODS: Medical records of the school health care services in Stockholm, Sweden, were reviewed for people born between 1960 and 1969. Altogether 600 persons with signs of atopic dermatitis ("cases") and 600 matched controls without eczema ("controls") were identified. Of these people, 405 cases and 378 controls answered a postal questionnaire focusing on choice of job, occupational exposure, past and present skin disease, and change of job due to eczema. RESULTS: The proportions of cases and controls in jobs with a high risk of hand eczema were similar, as was the exposure to water, detergents, chemicals, and hand washing. The self-reported cumulative prevalence of hand eczema was 42% for the cases and 13% for the controls (P<0.001). The 1-year prevalence was 24% for the cases and 9% for the controls (P<0.001). Among the cases, 9% reported a change of job due to eczema compared with 2% of the controls (P<0.001). The corresponding proportions of sick leave were 10% and 2% (P<0.001). CONCLUSIONS: In conclusion, a history of atopic dermatitis in childhood does not seem to influence the choice of job nor hazardous occupational skin exposure. It does, however, mean an increased risk for job changes, sick leave, and medical consultations, mainly due to the increased risk of hand eczema.

Absenteeism↗
PubMed2004

Self-reported skin morbidity among adults: associations with quality of life and general health in a Norwegian survey.

Life-quality studies among dermatologic patients have shown that chronic skin diseases have an impact on patients' lives. The purpose of this study was to assess the burden of skin morbidity at a community level. This was presented as prevalence of self-reported skin morbidity and dermatologic life-quality items. The association of skin disease and general health measures like feeling depressed and self-reported general health were measured. The method used was a questionnaire on self-reported skin complaints, including variables such as demographic, psychosocial, general health, dermatologic life-quality items. The design of the study was cross-sectional, with answers from 18,770 adult responders. The results confirmed that skin morbidity is common; itch was the dominating symptom. Younger adults reported more social problems as a result of skin problems than older. The life-quality domain most affected by skin disease was the social one. In a regression model skin disease was as well as rheumatism more strongly associated with feeling depressed than asthma, diabetes, and angina pectoris. Skin disease was also strongly associated with reporting poor general health, although less than other nondermatologic chronic diseases. In conclusion, in this study skin morbidity was strongly associated with general health measures among adults in a population-based setting. To the best of our knowledge these associations have not been described previously at a community level.

Adult↗
PubMed2003

Prevalence of self-reported eczema in relation to living environment, socio-economic status and respiratory symptoms assessed in a questionnaire study.

BACKGROUND: Potential links between eczema and obstructive pulmonary diseases have been postulated. Previously we have reported the prevalence of upper and lower respiratory diseases and the relation to environmental and socio-economic factors in a randomly selected adult population in southern Sweden using a postal questionnaire. In the present study we wanted to analyse the prevalence of eczema and its relation to socio-economic status, heredity factors and environmental factors in an adult population. METHODS: Self-reported eczema, upper and lower respiratory symptoms, asthma and Chronic Bronchitis Emphysema (CBE) were examined in 12,071 adults, aged 20-59 years, living in southern Sweden by using a postal questionnaire. There were comparable numbers of males and females in all age groups. Multiple logistic regression analysis (forward conditional) was applied to estimate the association between the proposed risk factors (heredity, self-reported asthma and CBE, nasal symptoms, socio-economic group, environmental factors, age, gender and smoking habits) and self-reported eczema. RESULTS: The response rate was 70.1%. In all, 1240 subjects (14.6%) stated that they had eczema. In all age cohorts self-reported eczema was more frequently reported by women than by men (p < 0.05). The prevalence of self-reported eczema among the economically active population varied from 17.1% to 8.2% with the highest rates among assistant non-manual employees. However, when controlling for age, gender and risk occupation there was no association between low social position and eczema. Living close to heavy traffic (OR = 1.45, 95% CI 1.25-1.67) and living seaside (OR = 1.17, 95% CI 1.01-1.35) but not urban/suburban living was associated with eczema. Heredity of eczema (OR = 5.77, 95% CI 5.02-6.64), self reported allergic rhinitis (OR = 2.31, 95% CI 2.00-2.68), self reported asthma (OR = 1.98, 95% CI 1.56-2.51) and self reported CBE (OR = 1.42, 95% CI 1.08-1.87) were all associated with eczema. CONCLUSIONS: In this epidemiological study we see that self-reported eczema is a common disease in an adult population especially among women. Eczema seems to be linked to environment factors, obstructive pulmonary diseases and rhinitis.

Adult↗
PubMed2003

Randomized clinical trials for psoriasis 1977-2000: the EDEN survey.

This study aims to describe the range of treatment comparisons, study designs and quality of reporting of randomized clinical trials (RCTs) in psoriasis published in a variety of medical and dermatological journals, and to analyze time trends with quality items. Hand-searching of clinical trials of psoriasis published from 1977 to 2000 in 13 medical or dermatological journals, selected as relevant to a European readership, was performed. A total of 249 trials published in 226 papers were classified as RCTs. Of these, 139 (55.8%) employed a parallel control group design, 107 (43.0%) studies adopted a self-control design and 3 (1.2%) a cross-over design. The median number of patients recruited per study was 40 (range 6-699). Overall, 55 different treatment modalities, including topical, ultraviolet-based, systemic, and other miscellaneous therapies were assessed. Only 31 (12.5%) RCTs were comparative studies of treatment modalities in different therapeutic classes. Most of the studies were short-term with a median study duration of 7 weeks (range 1-104), with only 18 studies (7.2%) lasting for more than four months. A variety of outcome measures including 44 different score systems were employed. According to the conclusions of the authors, 196 (78.7%) studies were judged to provide striking or definite observations in favor of one of the treatments examined. No important variations over time were documented for quality items. Based on our survey we have identified an enormous range of treatments that have been evaluated for psoriasis over the examined period. Most studies were short-term, and only a handful compared treatment options in different therapeutic classes. Since we did not examine all the relevant journals, the number of treatment options may be even greater than we have documented. There is an urgent need to reset the research agenda focusing on long-term comparative RCTs. Editors of major medical and dermatological journals are urged to take a role in improving the quality of RCT reporting.

Clinical Trials as Topic↗
PubMed2002

Rheumatoid arthritis, gold therapy, contact allergy and blood cytokines.

OBJECTIVE: To study the clinical and biochemical effects of a low starting dose for gold therapy in rheumatoid arthritis patients with a contact allergy to gold. METHODS: Serum cytokines were assayed before and 24 h after the first injection of gold sodium thiomalate (GSTM). RESULTS: Contact allergy to gold was found in 4 of 19 patients. Compared to gold-negative patients (starting dose: 10 mg GSTM), there was a larger increase in serum TNFalpha (p < 0.05), sTNF-R1 (NS), and IL-1 ra (p < 0.05) in gold-allergic patients. CONCLUSIONS: Cytokines are released in blood by GSTM in RA patients with gold allergy. To minimize the risk of acute adverse reactions the starting dose of GSTM should be lowered to 5 mg. Alternatively, patients should be patch-tested before gold therapy; in test-positive cases, 5 mg is recommended as the first dose.

Adult↗
PubMed2002

Contact allergy to the Asteraceae plant Ambrosia artemisiifolia L (ragweed) in sesquiterpene lactone-sensitive patients in southern Sweden.

Ambrosia artemisiifolia L. a classical cause of ragweed dermatitis in North America, is also found in Europe. 17 patients with contact allergy to sesquiterpene lactone (SL) mix were recalled for patch testing with extracts of North American and Swedish ragweed, the latter harvested in summer and autumn. 8/17 patients were test-positive to the American extract, 14/17 to the Swedish summer extract and 15/17 to the autumn extract. All patients except 1 were found to have a chronic hand eczema of the pompholyx type. 5/16 hand eczema patients had a flare-up of their pompholyx at patch testing. We concluded that patients with SL mix allergy are allergic to American as well as to Swedish ragweed. Pompholyx seems to be a frequent clinical picture in patients with SL mix allergy.

Adult↗