After screening, a total of 7828 questionnaires were sent out on the authors' behalf. Of these, 341 were returned as undelivered and 25 were returned as being unable to complete. Of the remaining questionnaires, 3462 (46.4%) were returned, of which 2474 had complete data and were included in the analyses. This gave a corrected completed response rate of 33.2%. Response rate varied by practice, from 17.2% to 44.5% (). The characteristics of sample participants are presented in , along with data from UK population surveys, to allow for comparison.
Participant characteristics of symptom survey sample and UK demographics
A total of 9024 symptoms in the previous 2 weeks were reported by responders. Over three-quarters reported experiencing at least one symptom, with half reporting having had between one and five symptoms. The number of symptoms experienced by any one individual ranged from 0 to 22, with the overall mean number being 3.66 (SD = 3.47) symptoms.
shows the mean number of symptoms experienced in the previous 2 weeks by patient characteristic among the full sample, and those with and without a chronic condition. In the full sample, there were significant associations between the mean number of symptoms and sex, age group, marital status, level of social support, number of children, level of education, housing tenure, employment status, annual household income, and smoking status. The mean number of symptoms was higher in those with a chronic condition than those without in all subgroups examined. Among those with a chronic condition, the patterns of association were very similar to the full sample, but age and number of children were no longer significant. Among those without a chronic condition there were significant associations only with sex, age, marital status, number of children, employment status, and annual household income.
Mean number of symptoms in the previous 2 weeks by participant characteristics
shows the reported 2-week prevalence of individual symptoms among the full sample, and those with and without a chronic condition. For the full sample, the reported prevalence varied substantially from 0.2% to 41.3%. The five symptoms most frequently reported were: feeling tired/run down, headaches, joint pain, back pain, and difficulty sleeping. These five symptoms remained the most prevalent among those with or without a chronic condition, although the ranked order changed slightly.
Reported prevalence in the previous 2 weeks for the full sample and those with and without a chronic condition
The rankings were less consistent for acute symptoms (such as sore throat, cold or flu symptoms) which tended to rank higher among those without a chronic condition. The reported prevalence for all 25 symptoms was higher among those who had a chronic condition than those who did not; these differences were statistically significant for 15 symptoms.
presents the unadjusted ORs for 2-week symptom prevalence by participant characteristics for the 20 most prevalent symptoms; the numbers of the other symptoms were too small for meaningful analysis. With the exception of ethnicity, all participant characteristics were found to be univariately associated with the prevalence of some symptoms, although this relationship varied by symptom. In general, women, those renting their home, those unable to work due to illness and others not in paid employment, ex- or current smokers, and those with a chronic condition reported having symptoms more often than those in the referent group for each characteristic. On the other hand, older age groups, those married or living together, those with medium/high social support, those with secondary or higher educational qualifications, and those with an annual household income of ≥£15 000 reported having symptoms less often than the referent groups.
Unadjusted odds ratios for reported 2-week prevalence of symptoms by participant characteristics
Although the patterns of association remained very similar, many of the factors significant at the univariate level lost their significance once adjusted for other variables (). The factors independently associated with the prevalence of each symptom varied considerably. Presence of a chronic condition, age, and employment status were the three factors most commonly associated with the 2-week prevalence of different symptoms. Sex, marital status, level of social support, household income, and smoking status were associated with fewer symptoms. Level of education, housing tenure, and ethnicity were not significantly associated with any symptoms after adjustment.
Adjusted odds ratiosa for reported 2-week prevalence of symptoms by participant characteristics
There was considerable variation in the reported characteristics of different symptoms (). Vomiting, coughing up blood, difficulty sleeping, and stomach/abdominal pain were most commonly rated as severe. Joint pain, psychological symptoms (feeling depressed, difficulty sleeping, nervousness/anxiety, and feeling tired/run down), and unintentional weight loss were the symptoms most commonly reported as being of long duration. The four psychological symptoms and vomiting had the highest levels of interference. Fainting and gastrointestinal symptoms (including vomiting, nausea/feeling sick, and loss of appetite) were most often associated with time off work. Symptom characteristics were further explored by sex and age (data not shown); few significant associations were found.
Proportion of people who reported each symptom as severe, of long duration, causing high interference, or resulting in time off work