The study was conducted at a university hospital in Sweden including 231 patients aged 25—69 without any organic cause for chest pain. Women, but not men, with UCP, had a higher prevalence of cardiovascular risk factors obesity, smoking, diabetes and hypertension compared with references. Aside from immigration the strongest independent psychosocial factors were mental strain at work and negative life events last year in men and stress at home in women. Concerning other medically unexplained chronic syndromes such as chronic widespread pain, irritable bowel syndrome and chronic fatigue there are studies showing that these syndromes share common traits. No study, so far, has formally compared psychosocial characteristics of patients with UCP with those in the general population using a case reference design. The aim of this study was to compare men and women with UCP to a randomly selected population sample free of clinical heart disease with regard to sleep problems, mental strain at work, stress at home, negative life events and HRQOL. Subjects and methods The study was carried out at Sahlgrenska University Hospital in Göteborg, Sweden from December 2002 to September 2003. Patients Data were collected during the daytime, Monday through Friday, at the ED and the medical ward. Consecutive patients between 25 and 69 years of age who were i evaluated for chest pain and judged by a physician to have no organic cause for the chest pain and ii free from any history of heart disease were included. In all, 337 patients were eligible for the present study. Eighteen patients declined participation, and 47 could not be investigated for logistical reasons e. In total, 231 patients 127 men and 104 women participated in the study 78%. Reference group Residents of Göteborg aged 25—69 years were recruited from the INTERGENE study. Totally 2422 1258 men, 1164 women residents of Göteborg were invited to participate in the INTERGENE study. In all, 1477 of those came to the screening during the study period. Additionally 380 191 men and 189 women did not complete the questionnaires regarding psychosocial factors, which were collected in a supplementary questionnaire distributed after screening. In total, 1069 individuals 490 men and 579 women participated 44%. Procedure All eligible patients were assessed and treated according to the routines of the ED. They were asked about participation by a nurse, and written and verbal information about all steps of the study was provided by the investigator. After written informed consent was obtained, the patients were assessed regarding their chest pain and asked to fill in a questionnaire concerning psychosocial factors before they were discharged from the hospital. The scale has been used on the same study population in a previous study where the alpha value for the patients with UCP was 0. The four items ask how often during the last month the subject has experienced the following: trouble falling asleep, trouble staying asleep, waking up several times per night, and waking up feeling tired and worn out after usual amount of sleep. The response alternatives are: not at all 0 , 1—3 days 1 , 4—7 days 2 , 8—14 days 3 , 15—21 days 4 , 22—31 days 5. The potential score is 0—20. A summary score was obtained by summing the responses for the two questions potential score, 2—10. Psychological stress at home was assessed by a single question related to stress. Stress was defined as feeling irritable or filled with anxiety or having sleep problems as a result of conditions at home. Negative life events were assessed in relation to the following 10 events: serious illness in a close relative; death of a close relative; worry about a close relative; divorce; being forced to move to a new home: being forced to change jobs; unemployment; insecurity at work; serious financial worries; an event leading to legal consequences. The response alternatives were: no 0 ; yes, earlier 1 ; yes, during the last year 2 ; yes, both during the last year and earlier 3. The potential score was 0—30. Each of the eight health concepts is measured on a scale from 0 to 100. Traditional risk factors for ischaemic heart disease were assessed. This was performed because subclinical disease amongst cases or referents cannot be entirely ruled out. Diabetes and hypertension were recorded by asking the patients and the references about earlier diagnosis verified by a physician. Weight and height were self reported in patients, but measured in references at the screening examination. Statistical analysis All statistical analyses were performed in SAS Statistical Analysis System version 8. Means, standard deviation and interquintile ranges were examined for continuous variables. Odds ratios were calculated by logistic regression to investigate associations between UCP and selected psychosocial variables. A multivariable analysis was conducted in two steps. Results Amongst the patients with UCP, education level was lower and the proportion of immigrants, were higher than amongst the reference group. There was little or no difference in the prevalence of smoking, diabetes and hypertension for male patients and their references. However, women with UCP had significantly higher prevalence of these factors, compared to women in the reference group. Both male and female patients were markedly more sedentary than references. Amongst men with UCP who reported experiencing sleep problems eight nights or more in the past month, trouble staying asleep was the most common complaint 42% vs. The most common complaint amongst women with UCP was trouble to fall asleep 29% vs. No other differences were found amongst women. Corresponding figures for women were 42% vs. Patients with UCP had also experienced more stress at home than did the references. Seventeen per cent of the men with UCP versus 5% of the references had stress at home. Amongst women corresponding figures were 26% vs. Total negative life events as well as negative events last year were twice as common in patients with UCP. Corresponding figures for women were 72% vs. Multivariable analysis of psychosocial variables and UCP All the psychosocial variables measured were higher in the UCP group than in the reference group OR 1. The multivariable analysis showed that more UCP patients were immigrants, independently of other factors. Mental strain at work and negative life events last year were independently associated with UCP in men and stress at home in women. In the final multivariable analysis were corrections for age, education and immigration status made but also for traditional risk factors for CHD. When a more parsimonious model was used, which adjusted only for age, education and immigration status the differences regarding mental strain at work and life events last year persisted in men. In women, stress at home persisted whilst the differences regarding total life events and life events the last year did not. Discussion In the present study, Swedish patients with UCP were more physically inactive, reported more sleep problems, more mental strain at work, more stress at home and more negative life events than did a reference group. Aside from immigration the strongest independent psychosocial factors were mental strain at work in men and stress at home in women. In addition, women, but not men with UCP, had a higher prevalence of cardiovascular risk factors obesity, smoking, diabetes and hypertension than their references. Our findings suggest that mental strain at work seems to be associated with UCP in men, but not in women. The UCP men were more often worried about being rushed at work and keeping up with their work load which can be a result of changed work conditions in society. The patients with UCP reported more total negative life events than did references. Nearly half of the patients had been worried about a close relative. Negative life events during the last year seem to be associated with UCP in men, as well as in women. Our results, however, do not include how many times a person had experienced the same event, limiting our ability to draw conclusions about total burden of negative life events. Our findings showed that immigration is associated with UCP in both men and women. It is important to note that 32% of the patients in our UCP group as compared to 16% of the references were immigrants. Eighteen per cent of the participants were immigrants. Similar results could be expected in present study but our findings showed that immigration is associated with UCP in both men and women. Unexplained chest pain patients reported greater difficulty in falling asleep and more frequently woke up feeling tired and worn out than did the references. In our study, 37% of the patients slept 6 h or less per night, a situation that could contribute to their UCP. The patients with UCP were more sedentary than the reference group and this may have contributed to their sleep problems. Despite the fact that patients with UCP had more sleep problems than references, the mulivariable analysis did not show that sleep problems were correlated with UCP. The multivariable analysis showed that hypertension was associated with UCP in women. Weight and height were self reported in patients which might underestimate the prevalence of overweight, and thus the true association with UCP. Life style factors as sleep, stress, decreased physical activity and excess weight presumably influence the cause and maintenance of UCP. For instance, sleep problems may be both causes and consequences of UCP. Additionally, our patients represent a sample from a single hospital, with data collection carried out only during daytime. This also could introduce bias if severity of UCP differs between night and daytime admissions. If, and to which extent the bias introduced by the selection of patients and references influences the validity of our results is unknown. Mental strain at work and negative life events last year are associated with UCP in men and stress at home in women. In addition, women but not men with UCP have higher levels of cardiovascular risk factors. All these factors are important to take into consideration when caring for patients with UCP, but further investigations are needed to provide a more comprehensive picture of this distressing symptom. Psychosocial stress and atherosclerosis: family and work stress accelerate progression of coronary disease in women. The Stockholm Female Coronary Angiography Study. Multiple stressors and coronary disease in women. The Stockholm Female Coronary Risk Study. J Intern Med 2007; 261: 245—54.
