Jan Størmer

Mean platelet volume is a risk factor for venous thromboembolism: the Tromsø study

See also Machin SJ, Briggs C. Mean platelet volume: a quick, easy determinant of thrombotic risk? This issue, pp 146–7.

The Tromsø Study: Physical Activity and the Incidence of Fractures in a Middle-Aged Population

We have studied the relation of occupational and recreational physical activity to fractures at different locations. All men born between 1925 and 1959 and all women born between 1930 and 1959 in the city of Tromsø were invited to participate in surveys in 1979–1980 and 1986–1987 (The Tromsø Study). Of 16,676 invited persons, 12,270 (73.6%) attended both surveys. All nonvertebral fractures (n = 1435) sustained from 1988 to 1995 were registered in the only hospital in the area. Average age in the middle of the follow‐up period (December 31, 1991) was 47.3 years among men and 45.1 years among women, ranging from 32 to 66 years. Fracture incidence increased with age at all locations among women, but it decreased with or was independent of age among men. Low‐energetic fractures constituted 74.4% of all fractures among women and 55.2% among men. When stratifying by fracture location, the most physically active persons among those 45 years or older suffered fewer fractures in the weight‐bearing skeleton (relative risk [RR] 0.6, confidence interval [CI] 0.4–0.9, age‐adjusted), but not in the non–weight‐bearing skeleton (RR 1.0, CI 0.7–1.2, age‐adjusted) compared with sedentary persons. The relative risk of a low‐energetic fracture in the weight‐bearing skeleton among the most physically active middle‐aged was 0.3 (CI 0.1–0.7) among men and 0.9 (CI 0.4–1.8) among women compared with the sedentary when adjusted for age, body mass index, body height, tobacco smoking, and alcohol and milk consumption. It seems that the beneficial effect on the skeleton of weight‐bearing activity is reflected also in the incidence of fractures at different sites.

Family history of myocardial infarction is an independent risk factor for venous thromboembolism: the Tromsø study

Summary.  Background: Recent studies indicate that arterial cardiovascular diseases and venous thromboembolism (VTE) share common risk factors. A family history of myocardial infarction (MI) is a strong and independent risk factor for future MI. Objectives: The purpose of the present study was to determine the impact of cardiovascular risk factors, including family history of MI, on the incidence of VTE in a prospective, population‐based study. Patients and methods: Traditional cardiovascular risk factors and family history of MI were registered in 21 330 subjects, aged 25–96 years, enrolled in the Tromsø study in 1994–95. First‐lifetime VTE events during follow‐up were registered up to 1 September 2007. Results: There were 327 VTE events (1.40 per 1000 person‐years), 138 (42%) unprovoked, during a mean of 10.9 years of follow‐up. In age‐ and gender‐adjusted analysis, age [hazard ratio (HR) per decade, 1.97; 95% confidence interval (CI), 1.82–2.12], gender (men vs. women; HR, 1.25; 95% CI, 1.01–1.55), body mass index (BMI; HR per 3 kg m−2, 1.21; 95% CI, 1.13–1.31), and family history of MI (HR, 1.31; 95% CI, 1.04–1.65) were significantly associated with VTE. Family history of MI remained a significant risk factor for total VTE (HR, 1.27; 95% CI, 1.01–1.60) and unprovoked VTE (HR, 1.46; 95% CI, 1.03–2.07) in multivariable analysis. Blood pressure, total cholesterol, HDL‐cholesterol, triglycerides, and smoking were not independently associated with total VTE. Conclusions: Family history of MI is a risk factor for both MI and VTE, and provides further evidence of a link between venous and arterial thrombosis.

The Tromsø Study: Registration of Fractures, How Good are Self-reports, a Computerized Radiographic Register and a Discharge Register?

Abstract: In order to compare different methods of fracture registration, we sought all nonvertebral fractures suffered during 8 years (1988–95) among 21 441 persons invited to a survey in 1979/80. We registered a total of 54 hip fracture cases through three separate sources (self-report, computer linkage to the local radiographic archives, discharge register), whereas forearm fractures (a total of 291 cases) were registered through two separate sources (self-report, computer linkage to the radiographic archives). The registration of fractures at other sites (a total of 1321 cases) were from one source (computer linkage to the local radiographic archives), and we have compared three ways of obtaining data from this single source (no ascertainment, ascertainment of records coded as fracture, ascertainment of all records). Ninety-three percent of all hip fractures and 97% of all wrist fractures in the entire study population were found by computer linkage to the radiographic archives, whereas the discharge register detected 87% of all the hip fractures. Computer linkage with ascertainment gave no overreporting of fractures. Among the 11 626 persons who answered a follow-up questionnaire in 1994/95, 97% (CI 84–100%) of all hip fractures and 72% (CI 66–78%) of all wrist fractures were self-reported. We conclude that a computerized search of radiographic archives is a viable method of fracture registration.

Abdominal obesity is essential for the risk of venous thromboembolism in the metabolic syndrome: the Tromsø study

Summary.  Background: The metabolic syndrome is a cluster of cardiovascular risk factors, including abdominal obesity, hypertension, dyslipidemia and insulin resistance, associated with increased risk of cardiovascular diseases and all cause mortality. Objectives: The purpose of the study was to assess the impact of the metabolic syndrome, and its individual components, on the risk of venous thromboembolism (VTE) in a prospective population‐based study. Methods: Individual components of the metabolic syndrome were registered in 6170 subjects aged 25–84 years in the Tromsø Study in 1994–1995, and first ever VTE events were registered until 1 September 2007. Results: The metabolic syndrome was present in 21.9% (1350 subjects) of the population. There were 194 validated first VTE events (2.92 per 1000 person‐years) during a mean of 10.8 years of follow‐up. Presence of metabolic syndrome was associated with increased risk of VTE (HR, 1.65; 95% CI, 1.22–2.23) in age‐ and gender‐adjusted analysis. The risk of VTE increased with the number of components in the metabolic syndrome (P < 0.001). Abdominal obesity was the only component significantly associated with VTE in multivariable analysis including age, gender, and the individual components of the syndrome (HR, 2.03; 95% CI, 1.49–2.75). When abdominal obesity was omitted as a diagnostic criterion, none of the other components, alone or in cluster, was associated with increased risk of VTE. Conclusions: Our study provides evidence for the metabolic syndrome as a risk factor for TE. Abdominal obesity appeared to be the pivotal risk factor among the individual components of the syndrome.

Breastfeeding protects against hip fracture in postmenopausal women: The Tromsø study

Despite reported bone loss during pregnancy and lactation, no study has shown deleterious long‐term effects of parity or breastfeeding. Studies have shown higher bone mineral density and reduced risk for fracture in parous than in nulliparous women or no effect of parity and breastfeeding, so long‐term effects are uncertain. We studied the effect of parity and breastfeeding on risk for hip, wrist and non‐vertebral fragility fractures (hip, wrist, or proximal humerus) in 4681 postmenopausal women aged 50 to 94 years in the Tromsø Study from 1994–95 to 2010, using Coxs proportional hazard models. During 51 906 person‐years, and a median of 14.5 years follow‐up, 442, 621, and 1105 of 4681 women suffered incident hip, wrist, and fragility fractures, and the fracture rates were 7.8, 11.4, and 21.3 per 1000 person‐years, respectively. The risk for hip, wrist, and fragility fracture did not differ between parous (n = 4230, 90.4%) and nulliparous women (n = 451, 9.6%). Compared with women who did not breast‐feed after birth (n = 184, 4.9%), those who breastfed (n = 3564, 95.1%) had 50% lower risk for hip fracture (HR 0.50; 95% CI 0.32 to 0.78), and 27% lower risk for fragility fracture (HR 0.73; 95% CI 0.54 to 0.99), but similar risk for wrist fracture, after adjustment for age, BMI, height, physical activity, smoking, a history of diabetes, previous fracture of hip or wrist, use of hormone replacement therapy, and length of education. Each 10 months longer total duration of breastfeeding reduced the age‐adjusted risk for hip fracture by 12% (HR 0.88; 95% CI 0.78 to 0.99, p for trend = 0.03) before, and marginally after, adjustment for BMI and other covariates (HR 0.91; 95% CI 0.80 to 1.04). In conclusion, this data indicates that pregnancy and breastfeeding has no long‐term deleterious effect on bone fragility and fractures, and that breastfeeding may contribute to a reduced risk for hip fracture after menopause.

Anthropometric Measures of Obesity and Risk of Venous Thromboembolism. The Tromsø Study

Objectives—The purpose of this study was to assess the impact of various obesity measures on identification of subjects at risk and their respective risk estimates for VTE in a prospective population-based study. Methods and Results—Measures of body composition such as body mass index (BMI), waist circumference (WC), hip circumference (HC), and waist-hip ratio (WHR) were registered in 6708 subjects aged 25 to 84 years, who participated in the Tromsø Study (1994–1995). Incident VTE-events were registered during follow-up until September 1, 2007. There were 222 VTE-events during a median of 12.3 years of follow-up. All measures of obesity exhibited significantly increased HR for VTE in multivariable models with highest risk estimates for WC in both genders. The risk of VTE increased across quartiles of BMI, WC, and HC in both genders, but not for WHR. WC identified more subjects at risk using established criteria for obesity. WC had the highest area under the curve in both genders in ROC analysis, and WC above ROC-derived cut-off values (WC ≥85 cm in women and ≥95 cm in men) were associated with HRs of 1.92 (95% CI: 1.05 to 3.48) in women and 2.78 (95% CI: 1.47 to 5.27) in men. Conclusions—Our findings indicate that WC is the preferable anthropometric measure of obesity to identify subjects at risk and to predict risk of VTE.

Progressively Increasing Fracture Risk With Advancing Age After Initial Incident Fragility Fracture: The Tromso Study

The risk of subsequent fracture is increased after initial fractures; however, proper understanding of its magnitude is lacking. This population‐based study examines the subsequent fracture risk in women and men by age and type of initial incident fracture. All incident nonvertebral fractures between 1994 and 2009 were registered in 27,158 participants in the Tromsø Study, Norway. The analysis included 3108 subjects with an initial incident fracture after the age of 49 years. Subsequent fracture (n = 664) risk was expressed as rate ratios (RR) and absolute proportions irrespective of death. The rates of both initial and subsequent fractures increased with age, the latter with the steepest curve. Compared with initial incident fracture rate of 30.8 per 1000 in women and 12.9 per 1000 in men, the overall age‐adjusted RR of subsequent fracture was 1.3 (95% CI, 1.2–1.5) in women, and 2.0 (95% CI, 1.6–2.4) in men. Although the RRs decreased with age, the absolute proportions of those with initial fracture who suffered a subsequent fracture increased with age; from 9% to 30% in women and from 10% to 26% in men, between the age groups 50–59 to 80+ years. The type of subsequent fracture varied by age from mostly minor fractures in the youngest to hip or other major fractures in the oldest age groups, irrespective of type and severity of initial fracture. In women and men, 45% and 38% of the subsequent hip or other major fractures, respectively, were preceded by initial minor fractures. The risk of subsequent fracture is high in all age groups. At older age, severe subsequent fracture types follow both clinically severe and minor initial incident fractures. Any fragility fracture in the elderly reflects the need for specific osteoporosis management to reduce further fracture risk.

Prioritisation of telemedicine services for large scale implementation in Norway

In late 2005, the Northern Norway Regional Health Authority requested an evaluation of all tested telemedicine services in northern Norway to clarify which were suitable for large scale implementation. A total of 282 reports from the Norwegian Centre for Telemedicine, the University Hospital of North Norway and the University of Tromsø were included in the study. Projects not focusing on secondary health care were excluded and 46 studies representing 21 topics entered the final analysis. They were analysed with a self-developed scoring tool focusing on five items. Eleven topics were concluded as being candidates for large scale implementation and grouped according to priority. The first priority topics were teleradiology, digital communication/integration of patient records and education. The second priority topics were teledialysis, pre-hospital thrombolysis, telepsychiatry and teledermatology. The third priority topics were paediatrics, district medical centres, tele-ophthalmology and tele-otorhinolaryngology. No priority was suggested for the projects in cardiology, endocrinology, geriatrics, gynaecology/obstetrics, pathology and nursing/care. User support, training, research ability, financial incentives and interaction between clinicians and ICT-personnel were considered as important factors in motivating health-care personnel to use telemedicine.

Neurosurgical teleconsultations in northern Norway

We carried out a prospective study of the effect of neurosurgical teleconsultations on patient management in northern Norway. The total number of teleradiology image transfers during an eight-month study period was 723. We recorded data on 99 (14%) of these teleconsultations, which concerned 92 patients; the remainder were transfers to other departments at our hospital and transfers of routine examinations from a small community hospital that did not have a radiologist. The neurosurgeon on call noted the clinical condition and response time for each consultation. The consequences of the teleconsultation and the eventual benefits of the image transfer were evaluated. All 10 referring hospitals in the region used the service. The median response time was 3 hours (range 1–21 hours) in emergency cases and 1 day (range 1–7 days) in ordinary consultations. The response time was significantly shorter for patients with head injuries (median 3 hours) than for those with intracranial tumours (median 24 hours). Image transfer was considered beneficial for the patient in 93% of the cases. Avoidance of unnecessary patient transfer, changes of treatment at the referring hospital on the advice of the neurosurgeon and initiation of emergency transfer occurred in 34%, 42% and 13% of cases, respectively. The results confirm that teleconsultations between referring hospitals and a regional neurosurgical service influence patient management and reduce the frequency of patient transfer.