Original articleUse of a cross-sectional survey to estimate outcome of health care: The example of anxiety and depression
Introduction
Population surveys are an important epidemiological tool because they are based on the principle that the sample of the target population surveyed is unselected by health care setting or membership of particular groups. Such survey methods are used to estimate the health care needs for a given problem in a population. In the particular example of neurotic disorders, the Epidemiological Catchment Area study [1] and the UK OPCS survey [2] have estimated the prevalence in the population for these conditions at approximately 15% and this figure would represent the overall likely need for health care.
Outcome of health care, in contrast, has been traditionally estimated by prospective studies, in particular randomized controlled trials. The generalizability of the results of trials is often limited by the selectivity of their participating populations, and a complementary method is to perform observational follow-up studies to determine what happens to a broad group of patients who receive the treatment or intervention in actual practice. Examples of such approaches in the field of neurotic disorders include the World Health Organization (WHO) international study on depression outcome [3] and the study of the influence of adherence to antidepressant treatment guidelines on subsequent relapse and recurrence of depressive illness [4].
So traditionally, distinct and different approaches have been used to determine need and outcome. Assessing both are key objectives in delivering effective health care. Local health care systems have adopted the survey as one approach to measuring need, but methods to assess outcome of care are less easily translated from research to a health service environment. It is curious that epidemiological surveys are assumed to identify need for health care, but will actually include groups of people who have already received health care, and who at time of the survey have either recovered or not recovered, as well as people who have symptoms but have not received care. All of this means that the traditional survey of need is also presenting the observer with a picture of the outcome of health care already received in that population.
To use a survey both as a measure of outcome of health care as well as health need, we have to know the prior health care provided for the condition. In the UK, the clinical general practice records of the population are continuous, irrespective of whether the patients move practice, and are life-long. More than 95% of the UK population are registered with general practitioners who provide access to most health care services within the National Health Service. Hence, these records can provide data on all clinical diagnoses and treatments in the registered population. By relating the previous health records of individuals to a cross-sectional survey, the survey results will represent an estimate of the outcome of earlier diagnoses and health care. Few studies have attempted to use retrospective case-control methods to assess outcome of health care, except in the field of screening [5] and isolated investigations of other topics [6].
Our study used a postal survey to assess the prevalence of health care needs for anxiety and depression in a population registered with a general practice in the UK, and we hypothesized that such a survey could also be used to estimate the outcome of health care. We used general practice data as the source of historical information about health care, and applied it to the health status determined by the population survey, to estimate the current outcome of primary health care for anxiety and depression in this population.
Section snippets
Design
The study was a population-based case-control study. There were two phases: phase 1 was a postal survey of the registered practice population and phase 2 a retrospective 12-month review of practice-held records of a sample of the surveyed population. Survey subjects who had current high or medium scores on a scale of anxiety or depression symptoms were compared with a control group of subjects with low scores.
Study population
As more than 95% of the British population are registered with a general practitioner,
Phase 1: Population survey
In the total survey sample of 4002, there were 34 patients who were temporarily registered patients, i.e., less than 3 months with the practice, so the adjusted survey response rate after the exclusion of this group was 66% (n = 2606). The number of patients with a high HAD score in the survey responders for anxiety or depression was 416 (16%); 506 (19%) patients had a medium score; and there were 1684 (65%) controls. The prevalence of probable anxiety and depression as shown by the high score
Study findings: population survey as an estimate of health care need
The questionnaire survey confirmed the high prevalence of anxiety and depression symptoms in the adult UK population. Figures for the high score group were comparable to those of other studies 1, 2, which have estimated the prevalence of neurotic disorders such as anxiety and depression at approximately 15% in the population. The associated demographic characteristics also confirm results from other studies 1, 2.
Study findings: population survey as an estimate of health care outcome
Patients with a high HAD score were more likely to have contacted the GP for any
Acknowledgements
North Staffordshire Health Authority supported UTK in a Public Health post during the project year and the Royal College of General Practitioners Scientific Foundation Board Grant funded part of the project. We are very grateful to all the patients and staff of the study practice. We would also like to thank Rob McCarney for his help in the survey data collection, Rhian Hughes for assistance in record data collection, and Paul Trinder for his comments on the earlier drafts of the paper.
References (25)
- et al.
Does screening by “PAP” smears help prevent cervical cancer? A case-control study
Lancet
(1979) - et al.
Screening for depression and anxiety in cancer patients, using the Hospital Anxiety and Depression Scale
Gen Hosp Psychiatry
(1993) - et al.
Psychotropic medication consumption patterns in the UK general population
J Clin Epidemiol
(1998) - et al.
Psychiatric disorders in America. The Epidemiological Catchment Area Study
(1991) - et al.
The prevalence of psychiatric morbidity among adults living in private households. OPCS Surveys of Psychiatric Morbidity in Great BritainReport No.1
(1995) - et al.
The effects of detection and treatment on the outcome of major depression in primary carea naturalistic study in 15 cities
Br J Gen Pract
(1998) - et al.
The effects of adherence to antidepressant treatment guidelines on relapse and recurrence of depression
Arch Gen Psychiatry
(1998) - et al.
Oral contraceptives and non-fatal myocardial infraction
JAMA
(1978) - Office of Population Census and Surveys (OPCS). Morbidity Statistics from General Practice. Fourth National Study...
- VAMP Vision. Practice health systems limited. London;...
The Hospital Anxiety and Depression Scale
Acta Psychiatr Scand
Psychiatric screening in general practicecomparisons of the General Health Questionnaire and the Hospital Anxiety and Depression Scale
J R Coll Gen Pract
Cited by (15)
Impact of non-cardiovascular disease comorbidity on cardiovascular disease symptom severity: A population-based study
2014, International Journal of CardiologyCitation Excerpt :The physical limitation (PL) summary score, which is the component shared by both questionnaires was used as a comparable measure of symptom-based limitation. In addition, study data available included age, gender, deprivation, body mass index (BMI), smoking status, alcohol, and hospital anxiety and depression (HAD) questionnaire on psychological status [33]. The Index of Multiple Deprivation (IMD) uses the individual patient postcode to indicate deprivation, and is a weighted score relating to income; employment; health; education, skills and training; barriers to housing, and access to local services; crime; and living environment [34].
Morbidity severity classifying routine consultations from English and Dutch general practice indicated physical health status
2008, Journal of Clinical EpidemiologyCitation Excerpt :In the United Kingdom [1] and the Netherlands, most of the population are registered with a general practitioner (GP), and in an average British practice there are an estimated 50,000 consultations per year [2]. Population-based consultation data provide an estimate of morbidity and have been used to study health needs relating to specific conditions [2,3], and to assess health care use as an outcome of primary care interventions [4,5]. The focus of attention in health care tends to be on arbitrarily defined chronic diseases, major life-threatening disorders such as cancer, or diseases that result in hospital admissions.
Clinical comorbidity was specific to disease pathology, psychologic distress, and somatic symptom amplification
2005, Journal of Clinical EpidemiologyCitation Excerpt :In the United Kingdom, all residents are registered with a family practitioner and so the clinical records in a general practice are a source of population-based data on all morbidity for which consultation is sought among its registered patients. Clinical records have been used to study health needs, health interventions, and health outcomes for individual diseases such as anxiety and depression [19] and diabetes mellitus [20]. Many practices code clinical contacts routinely using a standard classification that covers symptoms, minor illnesses, and chronic conditions.
The associations between psychological distress and cancer prevention practices
2005, Cancer Detection and PreventionAssessment of coverage rates and bias using double sampling methodology
2004, Journal of Clinical Epidemiology