Biomedical subjects

Knut Liestøl

Publications and source records attributed to Knut Liestøl.

8 recordsLinked to original sources

PubMed2005

Reasons for terminating an exercise test provide independent prognostic information: 2014 apparently healthy men followed for 26 years.

AIMS: We wanted to study whether reasons for terminating an exercise test might influence long-term mortality of healthy men, a previously unreported subject. METHODS AND RESULTS: During 1972-75, 2014 men aged 40-59, free from somatic diseases and not using drugs, underwent an examination programme including case history, clinical examination, various blood tests, and a symptom limited exercise ECG-test. The following reasons for test termination were noted: impaired breathing, lower limb fatigue, exhaustion (=combined lower limb fatigue and impaired breathing), high heart rate, abnormal blood pressure response, heart arrhythmias, increasing chest pain during exercise, marked ST-depressions during the test, and refusal to continue. Follow-up was 26 years. When adjusting for age, men who stopped exercising exclusively because of impaired breathing (n=178) had a 1.86-fold increased risk (95% CI 1.34-2.60; P=0.0002) of dying from coronary heart disease (CHD), a 1.64-fold increased risk (95% CI 1.32-2.03; P<0.0001) of dying from any cause, and a 3.47-fold increased risk (95% CI 2.24-5.12; P<0.0001) of dying from pulmonary causes compared with men having defined exhaustion (n=1376). After adjustment for age, smoking, total serum cholesterol, fasting blood glucose, systolic blood pressure, and physical fitness, impaired breathing remained significantly associated to an increased risk of dying from CHD, pulmonary disease, or any causes. CONCLUSION: Healthy men who stop bicycle exercising only because of impaired breathing have a high long-term CHD-, pulmonary-, and total-mortality, and such men may need further diagnostic scrutiny and follow-up.

Adult↗

PubMed2005

Blood pressure in the neonate: three non-invasive oscillometric pressure monitors compared with invasively measured blood pressure.

AIM: To compare blood pressure in neonates obtained from three different oscillometer blood pressure monitors (Dinamap, Criticare, Hewlett-Packard) with arterial blood pressure (Hewlett-Packard' invasive unit). STUDY DESIGN: A total of 32 randomized, non-invasive blood pressure series, each consisting of three measurements from each monitor, were obtained from 20 neonates (birthweight 531-4660 g). Each measurement was compared with the invasive pressure. RESULTS: Two factors appear to have a systematic effect on the difference between oscillometric and invasive pressure (the measurement deviance): the size of the infant, e.g., the arm circumference, and the monitor system. For small infants, the non-invasively measured value tends to be too high. The deviance is partly reversed for larger infants (dependency on size significant for mean and diastolic pressure, p < 0.001). The difference between monitor systems is clearly significant (p < 0.001). Hewlett-Packard gives the lowest pressure values for all pressures. Thus, Criticare and Dinamap tended to show values too high in the smallest infants, while Hewlett-Packard tended to give values too low in larger infants. Birthweight, present weight and arm circumference affected measurement deviance approximately equally strongly, while factors such as the infant's sex, need of breath support and umbilical or radial arterial line were non-significant. CONCLUSIONS: Blood pressure should preferably be measured invasively in severely ill neonates and preterm infants, being aware of pitfalls with measurements using different oscillometer monitors and the size/arm circumference of the infant.

Blood Pressure↗

PubMed2004

CGH-Explorer: a program for analysis of array-CGH data.

SUMMARY: CGH-Explorer is a program for visualization and statistical analysis of microarray-based comparative genomic hybridization (array-CGH) data. The program has preprocessing facilities, tools for graphical exploration of individual arrays or groups of arrays, and tools for statistical identification of regions of amplification and deletion.

Computer Graphics↗

PubMed2004

Exercise testing of healthy men in a new perspective: from diagnosis to prognosis.

AIM: It has recently been suggested that exercise testing may be more valuable prognostically than it is diagnostically in apparently healthy subjects. We wanted to compare the accuracy of CHD risk assessment based on classical risk factors with an assessment also based on multiple exercise test parameters. METHODS AND RESULTS: In 1972-75, 2014 apparently healthy men aged 40-60 had a symptom limited exercise test during a cardiovascular survey. Three hundred died from CHD during 26 years of follow-up. Compared to Cox regression models solely including classical risk factors (CRF), models also including multiple exercise test parameters (CRF+X) were clearly superior (P < 0.0001). Risk scores were computed based on the models. CRF and CRF+X risk scores often differed markedly; CRF+X scores were generally most reliable in both the high and low risk range. In smokers with cholesterol >6.5 mmol/l (n = 470), the CRF and CRF+X models identified 67 vs. 110 men at the highest CHD risk level according to European guidelines (34.2% vs. 38.2% CHD mortality). Three in five CRF+X-identified smokers with cholesterol >6.5 mmol/l had CHD mortality similar to the mean of all 2014 men. CONCLUSION: Integration of multiple exercise test parameters and conventional risk factors improved CHD risk assessment substantially--especially in smokers with high cholesterol.

Adult↗

PubMed2003

Attenuation caused by infrequently updated covariates in survival analysis.

This paper deals with hazard regression models for survival data with time-dependent covariates consisting of updated quantitative measurements. The main emphasis is on the Cox proportional hazards model but also additive hazard models are discussed. Attenuation of regression coefficients caused by infrequent updating of covariates is evaluated using simulated data mimicking our main example, the CSL1 liver cirrhosis trial. We conclude that the degree of attenuation depends on the type of stochastic process describing the time-dependent covariate and that attenuation may be substantial for an Ornstein-Uhlenbeck process. Also trends in the covariate combined with non-synchronous updating may cause attenuation. Simple methods to adjust for infrequent updating of covariates are proposed and compared to existing techniques using both simulations and the CSL1 data. The comparison shows that while existing, more complicated methods may work well with frequent updating of covariates the simpler techniques may have advantages in larger data sets with infrequent updatings.

Computer Simulation↗

PubMed2002

Updating of covariates and choice of time origin in survival analysis: problems with vaguely defined disease states.

This paper discusses survival analysis based on updated covariates with focus on proportional hazard regression in situations where some disease states may be vaguely defined. Analyses of a trial in liver cirrhosis are used to motivate the discussion. We use problems caused by inclusion of recordings from unscheduled follow-ups to illustrate the importance of appropriate coding of covariates and describe how such problems may be approached using appropriately 'lagged' covariates. The choice of time origin is discussed with emphasis on situations where disease initiation is difficult to define. Simulations are used to assess the effect of an erroneously specified time origin. It is argued that age or calendar time may frequently be sensible time variables.

Cohort Studies↗

PubMed2002

CMV disease in AIDS patients: incidence of CMV disease and relation to survival in a population-based study from Oslo.

CMV disease is an important cause of morbidity and mortality in patients with AIDS. The purpose of this study was to investigate the incidence of CMV disease in a well-defined population of AIDS patients with a high rate of autopsy. No such study has previously been published from Scandinavia. A total of 248 patients who developed clinical AIDS in Oslo during the period 1 January, 1983 to 31 December, 1995 were included. Autopsy was performed in 152 of 213 deaths (71.3%). CMV disease was diagnosed in 95 patients. In the autopsy group, 73 patients (48%) had CMV disease, and in 52 of these patients CMV disease was first detected at autopsy. Retinitis was the most frequent manifestation, followed by adrenalitis, pneumonitis, encephalitis and gastrointestinal disease. No intravenous drug users (IVDUs) were diagnosed alive with CMV disease. All patients diagnosed with CMV disease before death had evidence of CMV disease at autopsy despite anti-CMV treatment. CMV disease was associated with increased risk of death. We conclude that CMV disease was frequent in patients with AIDS during the study period, was associated with increased mortality and was often diagnosed too late for the administration of appropriate therapy.

AIDS-Related Opportunistic Infections↗

PubMed2002

Allele frequencies of apolipoprotein E gene polymorphisms in the protein coding region and promoter region (-491A/T) in a healthy Norwegian population.

This study examines the distribution of apolipoprotein E (APOE) alleles in a population of healthy male and female Norwegians (n = 798) below the age of 40. The -491A/T polymorphism of the promoter region of the APOE gene was also examined. A seminested polymerase chain reaction was applied in the genotyping. The results showed that the E3 allele had the highest frequency (0.744), followed by E4 (0.198) and E2 (0.058). The APOE frequencies found in this study differ significantly from those obtained in earlier Norwegian APOE phenotypings. The allele frequencies in the -491 site of the promoter region were 0.845 for the A allele and 0.155 for the T allele. The genotype frequency was highest for AA (0.707), followed by AT (0.277) and TT (0.016). Moreover, the A allele was in linkage disequilibrium to E4.

Adult↗