Svend Kreiner

Oral contraceptives and venous thromboembolism: a five-year national case-control study☆

The objective of this study was to assess the influence of oral contraceptives (OCs) on the risk of venous thromboembolism (VTE) in young women. A 5-year case-control study including all Danish hospitals was conducted. All women 15-44 years old, suffering a first ever deep venous thrombosis or a first pulmonary embolism (PE) during the period January 1, 1994, to December 30, 1998, were included. Controls were selected annually, 600 per year in 1994-1995 and 1200 per year 1996-1998. Response rates for cases and controls were 87.2% and 89.7%, respectively. After exclusion of nonvalid diagnoses, pregnant women, and women with previous thrombotic disease, 987 cases and 4054 controls were available for analysis. A multivariate, matched analysis was performed. Controls were matched to cases within 1-year age bands. Adjustment was made for confounding influence (if any) from the following variables: age, year, body mass index, length of OC use, family history of VTE, cerebral thrombosis or myocardial infarction, coagulopathies, diabetes, years of schooling, and previous birth. The risk of VTE among current users of OCs was primarily influenced by duration of use, with significantly decreasing odds ratios (OR) over time: <1 year, 7.0 (5.1-9.6); 1-5 years, 3.6 (2.7-4.8); and >5 years, 3.1 (2.5-3.8), all compared with nonusers of OCs. After adjustment for confounders, current use of OCs with second- (levonorgestrel or norgestimate) and third- (desogestrel or gestodene) generation progestins when compared with nonuse resulted in ORs for VTE of 2.9 (2.2-3.8) and 4.0 (3.2-4.9), respectively. After adjusting for progestin types and length of use, the risk decreased significantly with decreasing estrogen dose. With 30-40 microg as reference, 20 and 50 microg products implied ORs of 0.6 (0.4-0.9) and 1.6 (0.9-2.8), respectively (p(trend) = 0.02). After correction for duration of use and differences in estrogen dose, the third/second-generation risk ratio was 1.3 (1.0-1.8; p <0.05). In conclusion, use of OCs was associated significantly to the risk of VTE. The risk among current users was reduced by more than 50% during the first years of use. The risk increased more than 100% with increasing estrogen dose, and the difference in risk between users of third- and second-generation OCs, after correction for length of use and estrogen dose, was 33%.

Low back pain rating scale : validation of a tool for assessment of low back pain

Low Back Pain Rating scale is an index scale which includes measurements of pain intensity, disability, and physical impairment. The scale was designed to monitor the outcome of clinical trials of low back pain treatment. It has been validated in 58 patients following first-time discectomy. The scale rating can be rapidly carried out and requires no special aids. With slight modification it can be used in office and telephone interviews, as well as postal questionnaires. These modifications only slightly reduce the quantity of information gathered. In the study, a high rater agreement (97.7%) was found without level difference between two observers using the scale. The validation process included: construct validity, criterion-related validity and item bias, relative to Global Assessments pronounced by the patient and an experienced clinician. Low Back Pain Rating scale hs been shown to be valid and reliable in the assessment of low back pain.

Oral contraceptives and venous thromboembolism: a case-control study.

To assess the influence of oral contraceptives (OC) on the risk for venous thromboembolism (VTE) in young women, a 5-year case-control study including all women 15-44 years old suffering a first deep venous thrombosis or a first pulmonary embolism from all Danish hospitals, along with 1200 control subjects during the period 1994-1995, was conducted. Of 586 patient and 1200 control subject questionnaires sent out, 523 patient (89.2%) and 1074 control (89.5%) questionnaires were returned with an agreement to participate. After exclusion of women with nonvalid diagnoses, women who were pregnant, and women with previous VTE or acute myocardial infarction (AMI), 375 patients and 1041 control subjects were available for analysis. Potential tested confounders included: body mass index, length of OC use, family history of VTE, AMI, or stroke, smoking habits, coagulopathies, diabetes, years of schooling, certainty of diagnosis, previous births, and treated hypertension during any pregnancy. A multivariate analysis was performed. Estrogen dose had no influence on the risk for VTE. The risk for VTE among current users of OC was primarily influenced by duration of use, with significantly decreasing odds ratios (OR) over time: < 1 year; 5.1 (3.1-8.5); 1-5 years; 2.5 (1.6-4.1); and > 5 years; 2.1 (1.5-3.1), all compared with those for nonusers of OC. This trend was still significant after adjustment for progestin types. Without adjustment for duration of use, current users of OC with second generation (levonorgestrel or norgestimate) and third generation (desogestrel or gestodene) progestins had OR of 1.8 (1.1-2.9) and 3.2 (2.3-4.4), respectively. After correction for duration of use, however, no significant differences were found between users of OC with different types of progestins. In conclusion, OC increase the risk for VTE significantly. The risk among current users of OC is primarily influenced by duration of use. No difference in risk was found according to estrogen dose, and the difference in risk between different types of progestins was not statistically significant after adjustment for duration of use.

Differential item functioning in the Danish translation of the SF-36

Statistical analyses of Differential Item Functioning (DIF) can be used for rigorous translation evaluations. DIF techniques test whether each item functions in the same way, irrespective of the country, language, or culture of the respondents. For a given level of health, the score on any item should be independent of nationality. This requirement can be tested through contingency-table methods, which are efficient for analyzing all types of items. We investigated DIF in the Danish translation of the SF-36 Health Survey, using two general population samples (USA, n = 1,506; Denmark, n = 3,950). DIF was identified for 12 out of 35 items. These results agreed with independent ratings of translation quality, but the statistical techniques were more sensitive. When included in scales, the items exhibiting DIF had only a little impact on conclusions about cross-national differences in health in the general population. However, if used as single items, the DIF items could seriously bias results from cross-national comparisons. Also, the DIF items might have larger impact on cross-national comparison of groups with poorer health status. We conclude that analysis of DIF is useful for evaluating questionnaire translations.

Hormone replacement therapy and risk of non-fatal stroke

BACKGROUND The effect of postmenopausal hormone replacement therapy (HRT) on the risk of subtypes of stroke is as yet unclear. To investigate the effect of oestrogen and combined oestrogen-progestagen therapy on the risk of non-fatal haemorrhagic and thromboembolic stroke, we carried out a case-control study. METHODS From the Danish National Patient Register we identified all Danish women aged 45-64 years who had a non-fatal, first-ever cerebrovascular attack during 1990-92. Two age-matched controls were randomly selected for each case from the Danish National Person Register. Important correlates of hormone use and stroke, on which information was obtained from postal questionnaires, were controlled for by multivariate analyses based on log-linear graphical models. The analyses included data on 1422 cases classified in four subtypes of stroke (160 subarachnoid haemorrhage, 95 intracerebral haemorrhage, 846 thromboembolic infarction, 321 transient ischaemic attack) and 3171 controls. FINDINGS After adjustment for confounding variables and correction for the trend in sales of HRT preparations, no significant associations were detected between current use of unopposed oestrogen replacement therapy and non-fatal subarachnoid haemorrhage (odds ratio 0.52 [95% CI 0.23-1.22]), intracerebral haemorrhage (0.15 [0.02-1.09]), or thromboembolic infarction (1.16 [0.86-1.58]), respectively, compared with never use. Current use of combined oestrogen-progestagen replacement therapy had no significant influence on the risk of subarachnoid haemorrhage (1.22 [0.79-1.89]), intracerebral haemorrhage (1.17 [0.64-2.13]), or thromboembolic infarction (1.17 [0.92-1.47]). A significantly increased incidence of transient ischaemic attacks among former users of HRT and among current users of unopposed oestrogen may to some extent be explained by selection--HRT users being more aware of symptoms than non-users. INTERPRETATION Unopposed oestrogen and combined oestrogen-progestagen replacement therapy have no influence on the risk of non-fatal thromboembolic or haemorrhagic stroke in women aged 45-64 years.

Contraceptives and cerebral thrombosis: a five-year national case-control study☆

The object of this study was to assess the influence of oral contraceptives (OCs) on the risk of cerebral thromboembolic attacks (CTA) including thrombotic stroke and transitory cerebral ischemic attacks. A 5-year case-control study including all Danish hospitals was conducted. All women 15-44 years old suffering a first ever CTA during the period January 1, 1994 to December 31, 1998, were included. Controls were selected annually, 600 per year in 1994-1995, 1200 per year 1996-1998. Response rates for cases and controls were 88% and 90%, respectively. After exclusion of nonvalid diagnoses, pregnant women, and women with previous thrombotic diseases, 626 cases and 4054 controls were available for analysis. A multivariate matched analysis was performed. Controls were matched to cases within 1-year age bands. Adjustments were made for the following potential confounders: year, length of OC use, smoking, hypertension, migraine, family CTA, and years of schooling. There were 212 and 1208 current users of OCs among cases and controls, respectively. The risk of CTA among current users of OCs decreased significantly with decreasing estrogen dose (nonusers reference): OCs with 50 microg, 30-40 microg, 20 microg ethinyl estradiol (EE) and progestin-only pills implied adjusted odds ratios (ORs) (95% CI) of 4.5 (2.6-7.7), 1.6 (1.3-2.0), 1.7 (1.0-3.1), and 1.0 (0.3-3.0), respectively. Current users of OCs with second- (levonorgestrel or norgestimate) and third- (desogestrel or gestodene) generation progestins combined with 20-30 microg EE had ORs of CTA of 2.2 (1.6-3.0) and 1.4 (1.0-1.9), respectively. After correction for differences in estrogen dose, the third- to second-generation risk ratio was 0.6 (0.4-0.9; p = 0.01). In conclusion, high dose OCs and OCs with second-generation progestins were associated with the risk of CTA. The risk increased 2.5 times with estrogen dose increasing from 20 to 50 microg EE, and users of low-dose OCs with second-generation progestins had a 61% higher risk-association of CTA than users of OCs with third-generation progestins.

Can Readmission After Stroke Be Prevented? Results of a Randomized Clinical Study: A Postdischarge Follow-Up Service for Stroke Survivors

BACKGROUND AND PURPOSE About 50% of stroke survivors are discharged to their homes with lasting disability. Knowledge, however, of the importance of follow-up services that targets these patients is sparse. The purpose of the present study was to evaluate 2 models of follow-up intervention after discharge. The study hypothesis was that intervention could reduce readmission rates and institutionalization and prevent functional decline. We report the results regarding readmission. METHODS This randomized study included 155 stroke patients with persistent impairment and disability who, after the completion of inpatient rehabilitation, were discharged to their homes. The patients were randomized to 1 of 2 follow-up interventions provided in addition to standard care or to standard aftercare. Fifty-four received follow-up home visits by a physician (INT1-HVP), 53 were provided instructions by a physiotherapist in their home (INT2-PI), and 48 received standard aftercare only (controls). Baseline characteristics for the 3 groups were comparable. Six months after discharge, data were obtained on readmission and institutionalization. RESULTS The readmission rates within 6 months after discharge were significantly lower in the intervention groups than in the control group (INT1-HVP 26%, INT2-PI 34%, controls 44%; P=0.028). Multivariate analysis of readmission risk showed a significant favorable effect of intervention (INT1-HVP or INT2-PI) in interaction with length of hospital stay (P=0.0332), indicating that the effect of intervention was strongest for patients with a prolonged inpatient rehabilitation. CONCLUSIONS Readmission is common among disabled stroke survivors. Follow-up intervention after discharge seems to be a way of preventing readmission, especially for patients with long inpatient rehabilitation.

A Cox regression model for the relative mortality and its application to diabetes mellitus survival data.

A Cox-type regression model for the ratio between the mortality in a cohort and that in a reference population is introduced. By means of the model it is possible to include in the survival analysis both individual (possibly time-dependent) characteristics for the study cohort and changing trends in the mortality in the reference population. This is particularly relevant in long-term follow-up studies where there may be considerable changes in the mortality in the reference population. Estimation procedures in the model are discussed and large-sample properties of the estimators are outlined. The model is applied to the analysis of two sets of data concerning the survival among insulin-dependent diabetics in Denmark.

Construct validation and the Rasch model: functional ability of healthy elderly people.

The purpose of this study was to test the construct validity of a measure of functional ability, developed with the intention of achieving a high degree of variability and capacity for discriminating among a group of healthy elderly people. Data were collected from 734 70-year-old people in Denmark in the county of Copenhagen. Functional ability was measured with the traditional activities of daily living and with a classification system developed specially for healthy elderly people. Construct validity was tested by the Rasch model for item analysis, addressing specifically the internal validity by assessing the homogeneity of items under different conditions. The results show that the proposed measure of functional ability is a combination of six different dimensions, divided into 3 types: mobility function, lower limb function and upper limb function. With regard to these three types decreased functional ability can appear by either tiredness or reduced speed.

Happiness and Life Satisfaction in Advanced European Countries

Based on the European Value Survey 1999, this article analyzes happiness and life satisfaction in nine rich, industrialized countries with different levels of perceived happiness. Using graphical modeling, the statistical analysis showed that happiness and life satisfaction are related but are different concepts and that contextual as well as individual variables are important in explaining their variations. One of the most important results is that happiness depends on whether the respondent lives in a stable relationship and on country characteristics. Life satisfaction was related to the respondent’s feeling of control and his or her country of residence. In an aggregated analysis, the country-specific variables were analyzed, showing that social capital was the most important predictor of happiness.