Department of General Medicine, University Hospital of Wales, Cardiff
Department of Psychological Medicine, University of Wales College of Medicine, Cardiff
Department of Psychological Medicine, University of Wales College of Medicine, Cardiff
Correspondence: Dr Michael Kerr, Department of Psychological Medicine, University Hospital of Wales, Heath Park, Cardiff CF4 4XW.Tel: 029 2069 4033; Fax: 029 2061 0812; e-mail: kerrmp{at}cf.ac.uk
Declaration of interest No conflict of interest. C.M. was partly funded by a grant from Glaxo-Wellcome.
See editorial pp.
1011, this issue.
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Aims To describe the epidemiology of learning disability, the influence of deprivation on prevalence and the pattern of secondary care uptake, including the effect of institutionalisation.
Method A record-linkage study of secondary care contacts of 434 000 people between 1991 and 1997. A population with learning disability was identified; their secondary care contact was calculated and compared with the general population's.
Results The distribution of people with a learning disability (n = 1595) correlated significantly with deprivation. The presence of a learning disability hospital significantly affected care uptake. Place of residence also affected acute admission to the learning disability hospital. Former institution residents generated 212 admissions per 1000 patients; community patients generated 18 per 1000. The admission rate with any psychiatric diagnosis to any setting was 26.3 per 1000 people with a learning disability; 16.5% of such patients had a dual diagnosis.
Conclusions Health provision for people with a learning disability is affected by institutional provision.
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
![]() |
METHOD |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Data sources and record linkage
Data were available for all in-patient admissions (1991-97), out-patient
appointments (1991-96), attendances at accident and emergency departments
(A&E) (1993-96) and mortality (1993-97) for the resident population of
South Glamorgan. In addition, a learning disability register compiled by the
local social services department and a long-stay learning disability hospital
database were used to identify patients with learning disability.
These data underwent a process of record linkage in order to identify those records relating to the same individual patient and to identify those individuals with a diagnosis of learning disability. The principle and process of record linkage have been discussed previously (Gill et al, 1993) and have been used in various studies (Morgan et al, 1997; Currie et al, 1998). Briefly, partial identifiers (name, gender, date of birth, postcode and address) were combined and matched by using probabilistic algorithms. The discriminating power of each item was calculated and weighted for whether the identifier was common or comparatively rare. A composite matching score was then calculated.
Data for in-patient admissions were derived from the contract minimum data set required for all UK health authorities. Admissions are recorded as finished consultant episodes (FCEs), defined as an inpatient spell under the care of one hospital consultant. An FCE finishes with either a hospital discharge or a discharge to the care of another consultant. It is therefore possible for a single admission to generate multiple FCEs.
Identification of patients
Patients with learning disability were identified by: (a) inclusion on the
social services district register; (b) an in-patient admission within the
learning disability speciality or with a diagnostic code of mental handicap
(ICD-9 317-319 or ICD-10 F70-79; World Health Organization,
1978,
1986); (c) an out-patient
appointment in the learning disability speciality; (d) inclusion on a
long-stay learning disability hospital data set.
Analysis
For calculations of period prevalence and relative risk, the age- and
gender-stratified 1996 population estimate for South Glamorgan was used as a
denominator. The numerator was the total number of patients identified with
learning disability excluding those known to have died before 1 January 1997.
No adjustment was made for migration to or from South Glamorgan. All hospital
activity was calculated for the 1996 prevalent populations.
Patients with learning disability were classified into three groups. Those present on the long-stay learning disability hospital data set in 1996 were defined as the institutional population. Those who had been resident in the learning disability hospital (that is, admitted before 1991 with a length of stay in excess of 365 days) but discharged before 1996 were defined as the ex-institutional population, and those recorded as never resident in the learning disability hospital were defined as the community population.
Townsend index of social deprivation
By identifying each individual with learning disability, we were able to
estimate the prevalence of learning disability in each district ward on the
basis of 1996 population estimates derived from the 1991 census. These
prevalence figures were standardised by age and correlated to the Townsend
index of material deprivation using the Pearson correlation coefficient. The
Townsend index has four key variables: proportion of population of working age
unemployed; proportion of households without a car; proportion of households
overcrowded (defined as households with more occupants than rooms); and
proportion of households not owner-occupied. A Townsend score of zero reflects
the average for the UK. A positive Townsend score indicates material
deprivation, with higher scores representing higher degrees of deprivation. A
negative Townsend score represents comparative affluence.
RESULTS
Prevalence
In 1996, the estimated resident population of South Glamorgan was 434 000. We identified 1595 patients with learning disability, a prevalence per 1000 of 4.1 for males and 3.2 for females. The prevalence for the City of Cardiff was 4.0 per 1000, while it was 2.7 for the semi-rural Vale of Glamorgan. Figure 1 shows the prevalence of learning disability plotted against age for both genders. There was a wide variation in prevalence with age, with peaks of 7.0 and 5.4 for males and females respectively in the age group 35-44 years. We identified 134 subjects (8.4%) as resident in long-term institutional care. Of the 1461 community patients, 76 (5.2%) were identified as ex-institutional patients discharged into the community after 1 April 1991.
|
Social deprivation
Figure 2 shows the
relationship between social deprivation and prevalence of learning disability
by district ward, after excluding those cases in long-term institutional care.
There was a strong correlation between deprivation and prevalence
(r=0.77, P <0.001). The correlations for three age bands
were r=0.43 (0-24 years), r=0.80 (25-64 years) and
r=0.38 (65 and over).
|
Acute in-patient activity
Between 1991 and 1997, there were 560 408 FCEs in the acute specialities.
Of these, 2422 (0.43%) involved patients with learning disability. These
patients consumed 0.43% of total bed-days. Mean length of stay for learning
disability patients was 4.37 days, compared with 4.94 for the
non-learning-disability population. The standardised admission ratios for
patients with learning disability were 4.63 (95% CI 3.79-5.47) for dentistry
specialities, 1.83 (95% CI 1.74-1.92) for the medical specialities and 0.64
(95% CI 0.59-0.69) for the surgical specialities. Admission rates for patients
with and without learning disability are shown in
Fig. 3.
Table 1 shows a breakdown of
admission rates and length of stay for the major medical and surgical
specialities.
|
|
Patients with learning disability registered in a long-term care institution and those always resident in the community had almost identical non-psychiatric admissions rates (239 and 240 per 1000 respectively). Those patients discharged from long-term institutional care had a higher admission rate (360 per 1000). The standardised admission ratio for those within institutional care compared with those in community care was 0.97 (95% CI 0.63-1.31). For emergency admissions this ratio was significantly reduced to 0.59 (95% CI 0.27-0.91).
The mean length of stay for institutional patients (2.1 days) was considerably lower than that of those in community care (5.3 days) and that of ex-institutional patients in community care (3.3 days). For emergency admissions, the respective figures were 2.9, 6.2 and 8.3 days.
Overall, total numbers of non-psychiatric hospital days per 1000 patients per annum were 492 for those in institutional care, 1270 for those in residential care and 1200 for the ex-institutional patients.
Psychiatric illness and activity
Of those patients we identified with learning disability, 263 (16.5%) were
identified as having had a contact within secondary care (in- or out-patient)
involving a primary or secondary diagnosis of psychiatric illness. Psychiatric
comorbidity was more prevalent among the ex-institutional group (42.1%) than
among those in institutional care (11.3%) or community care (15.6%).
Table 2 shows the admission rate per 1000 population for a primary ICD-10 diagnosis of psychiatric illness. Patients with learning disability accounted for 246 (1.37%) of all psychiatric in-patient admissions and 341 (0.8%) of all out-patient appointments.
|
Mental handicap services
There were a total of 490 FCEs in the learning disability speciality with
an admission dated after 31 March 1991. Of these, 198 involved patients
resident in the long-stay institution. These admissions therefore represent
either initial admissions or readmissions from an acute care provider.
Patients who had previously been discharged from the long-stay learning
disability institution generated 113 admissions, an annual admission rate of
212 per 1000 patients. This compares with an admission rate of 18 per 1000 for
those community patients never resident in the institution. Mean lengths of
stay for these two groups were 285 days and 114 days respectively.
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Relationship with social deprivation
We report a positive correlation between prevalence of learning disability
and social deprivation. This correlation may be explained largely by a
concentration of social care homes within less affluent areas. However, the
relationship is also apparent (although weaker) in the younger age groups
where patients will be resident within the family home. This may indicate the
presence of aetiogical factors associated with social deprivation that predict
learning disability, although there must be doubt over the direction of
causality. Caring for a patient with learning disability may involve financial
hardships and consequent social drift. These areas demand further
exploration.
Utilisation of non-psychiatric health services
Overall, patients with learning disability are not excessive users of
non-psychiatric in-patient care in terms of number of admissions or length of
stay, although there is considerable variation by speciality. Learning
disability patients tend to use more medical beds than other patients but have
less uptake within the surgical specialities. The first fact may reflect a
greater prevalence of certain conditions such as epilepsy in the learning
disability population, while the reduction in surgical care may be partly
explained by reduced uptake of obstetric and gynaecological care (see
Table 1). The lower mean length
of stay, as compared with the general population, appears to be
counter-intuitive in a population with high morbidity.
Patients in institutional care are likely to endure greater morbidity than those cared for in the community (Corbett, 1979; McGrother et al, 1996; McDermott et al, 1997), yet this is not reflected in acute hospital usage. Overall admissions are similar, although length of stay for the hospital residents is significantly shorter. It seems likely that a degree of acute medical care is provided within these institutions, reducing the length of stay in other hospitals. Our data therefore provide evidence for a hidden service provided by long-stay learning disability institutions that may be lost with the shift towards community-based care a finding which appears to be contradicted by the experience of the ex-institutional patients, who also have fewer emergency admissions. However, this population is frequently readmitted, for considerable periods, into the long-stay learning disability hospital, which again may offer acute care.
Psychiatric comorbidity
The data on psychiatric comorbidity dual diagnosis are interesting: 16.5%
of the learning disability population have contacts coded for psychiatric
diagnosis. While our figures are not synonymous with prevalence across the
full range of diagnosis for severe psychiatric illness, which one would expect
to lead to admission within a seven-year period, they represent a proxy for
prevalence. In fact, our estimate of the prevalence of schizophrenia of 30.1
per 1000 compares with other published figures in the learning disability
population (Doody et al,
1998).
Psychiatric care contact is also influenced by this institutional factor. This factor is striking in connection with admission to learning disability psychiatry, with high rates for the recently discharged institutional patients. Patients with a learning disability will continue to need acute psychiatric service following the closure of the institution.
The health care uptake of people with a learning disability is different from that of the general population. The spread of speciality contact appears to reflect the needs of this group. The presence of a learning disability institution had a significant influence on health provision; it remains to be seen whether other services will absorb this function after closure.
![]() |
Clinical Implications and Limitations |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
LIMITATIONS
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Corbett, J. A. (1979) Psychiatric morbidity and mental retardation. In Psychiatric Illness and Mental Handicap (eds F. E. James & R. P. Snaith), pp. 11 -26. London: Gaskell.
Currie, C. J., Morgan, C. L., Peters, J. P., et al (1998) The cost of hospital inpatient and psychiatric services for patients with epilepsy. Epilepsia, 39, 537 -544.[Medline]
Doody, G. A., Johnstone, E. C., Sanderson, T. L., et al (1998) Pfropfschizphrenie revisited. Schizophrenia in people with mild learning disability. British Journal of Psychiatry, 173, 145 -153.[Abstract]
Gill, L., Goldacre, M., Simmons, H., et al (1993) Computerised linking of medical records: methodological guidelines. Journal of Epidemiology and Community Health, 47, 316 -319.[Abstract]
Humphreys, S., Lowe, K. & Blunden, R. (1981) The administrative prevalence of mental handicap in the City of Cardiff: an examination of geographical distribution. Mental handicap in Wales Applied Research Unit Research, Report II . Cardiff: Welsh Office.
Kerr, M. (1998) Primary health care and health gain for people with a learning disability. Learning Disability Review, 3, 6 -18.
McClaren, J. & Bryson, S. E. (1987) Review of recent epidemiological studies of mental retardation: prevalence, associated disorders and etiology. American Journal of Mental Retardation, 92, 243 -254.[Medline]
McDermott, S., Platt, T. & Krishnaswami, S. (1997) Are individuals with mental retardation at high risk for chronic diseases. Family Medicine, 29, 429 -434.[Medline]
McGrother, C. W., Hauck, A., Bhaumik, S., et al (1996) Community needs for adults with learning disability and their carers: needs and outcomes from the Leicestershire register. Journal of Intellectual Disability Research, 40, 183 -190.[Medline]
Morgan, C. L., Currie, C. J. & Peters, J. R. (1997) Hospital utilisation as a function of social deprivation: diabetes versus non-diabetes. Diabetic Medicine, 14, 589 -594.[CrossRef][Medline]
Welsh Health Planning Forum (1992) Protocol for Investment in Health Gain: Mental Handicap (Learning Disabilities), Cardiff: Welsh Office.
World Health Organization (1978) The Ninth Revision of the International Classification of Diseases and Related Health Problems (ICD-9). Geneva: WHO.
World Health Organization (1986) The Tenth Revision of the International Classification of Diseases and Related Health Problems (ICD-10). Geneva: WHO.
Received for publication February 10, 1999. Revision received September 21, 1999. Accepted for publication September 21, 1999.