Subjects and sampling
A UK-wide population-based postal survey was undertaken in 2007/2008. Full details of the methods have been published previously [9
]. In brief, an age- and sex-stratified random sample of 8,000 adults aged 18-60 was drawn from 20 UK general practices following ethical approval. The sample size was calculated to ensure we could estimate the prevalence of the identified symptoms with narrow two-sided 99% confidence intervals around the prevalence estimates. Practices were recruited from the nationally representative Medical Research Council General Practice Research Framework. Convenience sampling was used to select practices that varied in size, geographical location, level of deprivation and area type. GPs screened the sample and excluded anyone who they felt it would be inappropriate to approach. Practice staff sent out questionnaire packs on our behalf. A reminder and replacement questionnaire was sent to non-respondents after three weeks.
The questionnaire inquired about the occurrence of 25 physical and psychological symptoms in the last two weeks. Symptoms were identified from previous literature and pilot work and ranged from those usually indicative of minor or self-limiting illness through to those which could be indicative of potentially serious conditions. A two week time period was chosen as this was considered long enough to enable many symptoms to have lasted their full course and for actions to have been taken, but was short enough to ensure good recall. For each symptom experienced, respondents indicated: the severity of the symptom at its worst; how long it had lasted; how much it had interfered with daily life; and how often they had experienced it in the previous year. Respondents were also asked to indicate all actions they had taken in the last two weeks to manage their symptom(s) from: did nothing; looked for information; discussed with friends and family; consulted a GP; phoned NHS 24/NHS Direct (a telephone advice line available 24 hours a day in the UK which co-ordinates all out-of-hours primary care services); consulted a nurse; consulted a pharmacist; consulted a complementary therapist; took over-the-counter (OTC) medications; took prescribed medications; other, please specify. Comprehensive data were also collected on respondent characteristics including: gender, age, marital status, social support, education, housing, employment, household income, ethnicity, smoking, and the presence of a chronic condition.
A random sample of 30 GPs from Grampian, Scotland were sent a self-completion postal questionnaire asking them to rate the potential seriousness of each of the 25 symptoms being examined as either:
• A - a symptom not causing concern, usually indicative of trivial/self-limiting illness
• B - a symptom of moderate concern - neither trivial nor serious
• C - a symptom of concern that could be indicative of a serious condition or illness
Thirteen GPs (43%) completed the ratings. From their responses a simple five-level symptom seriousness index was developed: Level 1 (least serious) - most GPs rated the symptom as A, Level 2 - GPs rated the symptom as a mix of As and Bs, Level 3 - most GPs rated the symptom as B, Level 4 - GPs rated the symptom as a mix of Bs and Cs, Level 5 (most serious) - most GPs rated the symptom as C. Examination of agreement between the GPs found that 81% of the GPs rated the symptom at the level it was assigned to, 18% rated it at one level higher or lower than it was assigned to and 1% rated it at two levels higher or lower than it was assigned to. The symptoms assigned to each of the five categories are shown in column 1 of Table .
Actions taken for symptoms experienced in the last two weeks (proportion of symptoms)*
To minimize the chances of a type 1 error from multiple testing, a conservative p-value of < 0.01 was used to denote statistical significance. Basic descriptive analyses were used to examine the actions taken for all symptoms combined and for individual symptoms. Binary logistic regression was used to examine:
1. factors associated with each individual action taken for all symptoms combined.
2. factors associated with a) the use of lay-care (looked for information, discussed with friends and family, took OTC medications and/or reported the use of other lay-care strategies) and b) the use of primary care health professionals (consulted a GP, nurse, pharmacist, complementary therapist and/or phoned NHS24/NHS Direct) for individual symptoms.
The first analysis was undertaken to explore the factors associated with each of the individual actions. The second analysis was undertaken to allow the effect of individual symptom characteristics such as severity to be investigated and because combining symptoms can mask significant variations [10
]. In the second analysis the actions taken had to be aggregated due to small numbers and only the 12 most prevalent symptoms could be examined.
Unadjusted and adjusted odds ratios and 99% confidence intervals were calculated. For consistency across the models, odds ratios were adjusted for all other variables being tested. In analysis 1, odds ratios were adjusted for all participant characteristics (gender, age, marital status, social support, education, housing, employment, household income, ethnicity, smoking, presence of a chronic condition) and number of symptoms experienced in the last two weeks. In analysis 2, odds ratios were adjusted for all participant characteristics and four symptom characteristics (severity, duration, interference with life and recent experience). For ease of reporting, responses to questions about symptom characteristics were categorised as: 'not severe' (mild, tolerable or moderate) and 'severe' (severe or extremely severe); 'short duration' (<1 day, 1-2 days, 3-4 days, 5-6 days), 'medium duration' (1-4 weeks) and 'long duration' (>4 weeks); 'low interference' (not at all, slightly or moderately) and 'high interference' (quite a bit or extremely); 'no recent experience' (had not experienced the same symptom in the previous year) and 'recent experience' (had experienced the same symptom in the previous year).