Hospitalisation in adults with intellectual disabilities compared with the general population in Norway.

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Journal of Intellectual Disability Research

doi: 10.1111/jir.12255

365 VOLUME

60 PART 4 pp 365–377 APRIL 2016

Hospitalisation in adults with intellectual disabilities compared with the general population in Norway S. Skorpen,1 M. Nicolaisen2 & E. M. Langballe2 1 Norwegian National Advisory Unit on Ageing and Health, Vestfold Hospital Trust, Norway 2 Norwegian National Advisory Unit on Ageing and Health, Vestfold Hospital Trust, and Department of Geriatric Medicine, Oslo University Hospital, Norway

Abstract Background Previous studies have found that adults with intellectual disabilities (ID) are hospitalised more often than the general population (GP). This study investigates hospital discharge rates and main diagnostic causes for hospitalisation among administratively defined people with ID compared with the GP in Norway. Method Data from the Norwegian Labour and Welfare Service was combined with data from the Norwegian Patient Register (Ntotal = 1 764 072 and NID = 7573) for the period 2008–2011. Data from a Norwegian patient report generator and Statistics Norway are also analysed. Results During the study period, 11% of people with ID and 11.5% of the GP were admitted to hospitals. The length of the average hospital stay was just over 4 days for both groups. Among those who were hospitalised, the majority were only admitted to hospital once during the study period: ID 66% and GP 70%. People with ID were admitted somewhat more often than people in the GP. Contrary to the GP, adults with ID were more frequently hospitalised at a younger age and less frequently at old age. The most common International Classification of Diseases diagnostic group for hospitalisation among people with ID is injury, poisoning and certain other Correspondence: Stine Skorpen, Norwegian National Advisory Unit on Ageing and Health, Vestfold Hospital Trust, Norway (e-mail: [email protected]).

consequences of external causes, whereas for the GP, it is diseases of the circulatory system. Conclusion This study finds that the proportion of people being hospitalised per year is statistically, but only slightly, different among adult people with ID and the GP. The results must be interpreted in light of the organisation of the health care system in Norway. Keywords adults, discharge diagnosis, hospitalisation, inpatient, intellectual disability

Introduction The general ageing of the populations is likely to put more pressure on the health care systems, including the hospitals. More people with intellectual disability (ID) than just a few decades ago also live to experience adulthood and old age (Patja et al. 2000; Torr et al. 2010; Haveman et al. 2011; Coppus 2013). Adults and elderly people with ID have a higher incidence of morbidity compared with the general population (GP) (Haveman et al. 2010; Hermans & Evenhuis 2014; Burke et al. 2014), and genetic predispositions for physical or psychological disorders in addition to the primary diagnosis are relatively common (Davis et al. 2014; Malt et al. 2013; Myrbakk & von Tetzchner 2008). However, people with ID often receive poorer health services compared with the GP. This has been shown in international and Norwegian studies and is recognised by national health authorities, professionals, families and

© 2016 MENCAP and International Association of the Scientific Study of Intellectual and Developmental Disabilities and John Wiley & Sons Ltd


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60 PART 4 APRIL 2016

366 S. Skorpen et al. • Hospitalization in Adults with ID

individuals with ID (The National Institute on Intellectual Disability and Community 2007; Robertson et al. 2011; Davis et al. 2014). The socioeconomic status of people with ID is often low because of a lack of opportunities and abilities. This, in turn, affects their entire lives, as they become dependent on their social, political, cultural and material environments (Hogg, J., Lucchino, R., Wang, K., Janicki, M.P., & Working Group 2000; The National Institute on Intellectual Disability and Community 2007; Emerson & Hatton 2014). Information about health and screening opportunities intended for the GP are seldom adjusted to accommodate the special needs of people with cognitive impairments (Hanna et al. 2011). This means that people with ID often have low health literacy and seldom receive health education that would enable them to participate in their own health decisions (The National Institute on Intellectual Disability and Community 2007; Ward et al. 2010). Care workers may also feel that they lack knowledge to recognise health problems and skills to promote health literacy (The National Institute on Intellectual Disability and Community 2007; Catona et al. 2012). Hence, people with ID are exposed to several social determinants that can severely affect their health (Adler & Stewart 2010; Emerson et al. 2012; Emerson & Hatton 2014). After 1991, all institutions for people with ID in Norway were closed. Today, people with ID live in community settings. Specified need for care and treatment are regulated in the social service legislation. Primary health care services are provided by the municipality, and the specialist health care service is responsible for hospital services. However, the lines of responsibility can unfortunately be unclear in individual cases (The National Institute on Intellectual Disability and Community 2007 and 2013). Because of the closing of the institutions for people with ID, habilitation service, as part of the specialist health care service, have been established in every county in Norway. The habilitation services offer both inpatient and outpatient services for people with ID and cooperate closely with the primary health care. The service is divided into two sections; children and youth habilitation and adult habilitation. In the habilitation service health care professionals, such as doctors, psychologists, learning disability nurses and others, works in a multidisciplinary setting that covers

assessment, treatment, controls and health training for people with ID. Reports on the health status for adults with ID in Norway are comparable with similar reports from other industrialised countries (The National Institute on Intellectual Disability and Community 2007; Haveman et al. 2010). Like Health Action Plans, Norway has individual plans (IP) to support health monitoring. Anyone who needs long-term, coordinated health care services has the right to an individual plan. A 2013 report from the habilitation service found that only a few people with ID have an IP and even fewer among the oldest (Norwegian Directorate of Health 2015, p. 15). Studies from Canada and England show that adults with ID are hospitalised more often than the GP (Balogh et al. 2010; Glover & Evison 2013). Balogh et al. (2010) reported that people with ID are consistently hospitalised for ambulatory care sensitive conditions (ACSC) at a higher rate than people without an ID in Manitoba, Canada. They also found a large discrepancy in the rates of hospitalisation in the 30–39-year-old age group for people with and without ID. Glover & Evison (2013) used their best estimate of the number of people aged 18 and over in the population of England with and without ID and suggested that the crude rate of emergency admissions for ACSCs was 76 admissions per 1000 each year for adults with ID-associated conditions. This is roughly five times the rate for people without ID (15 per 1000). Studies from Israel and Denmark show that adults with Down syndrome (DS) are more often hospitalised and for a longer duration than the GP (Tennenbaum et al. 2011; Zhu et al. 2013). This is the first study to investigate hospitalisation in adults with ID compared with the GP in Norway. In addition, this study investigates the age group differences in hospitalisation in people with ID and in the GP and the most common discharge diagnoses.

Methods Sample Based on criteria from the International Classification of Diseases (ICD-10) and the World Health Organisation, it is estimated that 1.5% of the five million people living in Norway today have an ID, that is, approximately 75 000 people. However, most



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have a mild form of ID and are not diagnosed or registered in any social welfare system (White Paper 45 2012-2013). From national registers, the prevalence of administratively defined people with ID in Norway is estimated to be between 44 and 45 per 10 000 inhabitants (Holden & Gitlesen 2006; Jakobsen 2007; Søndenaa et al. 2010). According to Søndenaa et al. (2010), a total of 21 045 people with ID were reported to be receiving social benefits. Adults with ID in Norway who receive social benefits provided by the government are recorded in the register of the Norwegian Labour and Welfare Service (NAV). In this study, the NAV register was used to identify people with ID who receive benefits because of their disabilities, as well as individuals with ID who receive an old age pension. All hospitalisations in Norway are registered in the Norwegian Patient Register (NPR) by main diagnosis at discharge using the ICD-10. To identify inpatients with ID who are older than 16 years, information from the NAV register was combined with data from the NPR. Official statistics about the number of inhabitants in Norway in different age groups was retrieved from Statistics Norway (www.ssb.no). Our sample includes people diagnosed with ID (not further specified) (F70–F79) and DS (Q90). Because most people with mild ID are not diagnosed or registered in any social welfare system (White Paper 45 2012-2013), we assume that the majority of those with ID in the included sample have moderate to severe levels of ID. In 2011, 15 140 people with ID (16 years or older) were registered in the NAV. All the statistical analyses in this paper are based on the assumption that the share adult population with ID included in the present data set is about 0.45% of the GP.

NPR data was used to identify hospitalisation per year during the period 2008–2011. NPR combined the data from the NPR and NAV on an individual level and sent it to us as anonymous data in three separate SPSS files, including hospital discharge diagnosis (ICD-10, three characters), days hospitalised and 5-year age groups. The total sample includes N = 1 764 072 persons aged 16–89 years old, of whom 7573 were persons with a known ID. For people with ID, but not for the GP, the data yielded information on the primary discharge diagnosis for each stay (Table 1). To investigate the primary discharge diagnosis in the GP, an additional dataset was retrieved from a NPR report generator (Norwegian Patient Register 2011; Labour & Service 2011). Because the NPR report generator does not include information on hospital admission for people over the age of 79 years, the figures reported in Table 2 and Table 4 are for the age range 16–79 years. It should be noted that the data presented in Table 3 was retrieved from Statistics Norway and is only available in 10-year intervals. The Regional Committees for Medical and Health Research Ethics and Norwegian Social Science Data Services (NSD) approved this project.

Statistical analysis Univariate and bivariate analyses were conducted. A Pearson chi-squared test was used to investigate whether the number of admissions among those hospitalised during the study period (2008–2011) was the same among those with ID as among the GP. A two-sample comparison of proportions was performed to identify whether people with ID were

Table 1 Number of hospital admissions among those hospitalised in Norway during the period 2008–2011, people with intellectual disability (ID) and the general population (GP)

People with ID

The general population

Total

Number of admissions

%*

(N)

%*

(N)

%*

(N)

1 2 3 or more

66.0 18.8 15.2

(4999) (1425) (1149)

70.0 16.9 13.1

(1 228 676) (297 342) (230 481)

69.9 16.9 13.1

(1 233 675) (298 767) (231 630)

*The percentage of people who had one, two or three or more admissions among those who were hospitalised during the period 2008–2011. 2 People with ID were hospitalized significantly more often than the GP, Χ (2, N = 1 764 072) = 56.77, P < 0.001.



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Table 2 The length of hospital stays among people with intellectual disability (ID) and the general population (GP), 16–79 years old (2011)

Persons with ID Length of stay 0 day 1 2–5 6–10 11–20 More than 3 weeks Total

N 447 952 1228 419 185 111 3342

GP %

N

%

13.4 28.5 36.7 12.5 5.5 3.3 99.9

68 714 161 820 257 430 76 737 33 716 17 039 615 456

11.2 26.3 41.8 12.5 5.5 2.8 100.1

The analysis is carried out separately for the two groups. The figures for persons with ID are from the NPR data. The figures for inpatients among the GP are retrieved from the NPR report generator (Norwegian Patient Register 2011). Table 3 Hospital admissions in different age groups in Norway in 2011

Age groups

N, admissions ID

N, ID*

IR**, ID

N, admissions GP

N, GP

IR, GP***

16–29 30–39 40–49 50–59 60–69 70–79 80–89 Total

245 295 326 401 395 255 95 2012

4011 3044 3203 2789 2007 1324 823 17201

0.06 0.10 0.10 0.14 0.20 0.19 0.12

71 655 66 577 51 914 58 151 74 328 63 418 58 434 444 477

891 435 676 514 711 974 619 707 461 774 294 323 182 902 3 838 629

0.08 0.10 0.07 0.09 0.16 0.22 0.32

Expected IR, ID

IR ratio ID/GP

322 300 234 262 323 285 262 1989

0.75 0.98 1.40 1.53 1.22 0.89 0.36

SIR****

1.01

Standardized incidence ratio (SIR) among people with ID and the general population (GP) estimated based on the age distribution in the GP and the assumption that 0.45% of the GP is registered in NAV with ID. *Eligible people with ID in the GP assumed to be registered at NAV (0.45%) based on the age distribution in the GP. The figures for the GP are from Statistics Norway (www.ssb.no). **Incidence ratio (IR), ID: observed cases divided on expected cases for each age group in the group of people with ID. ***IR, GP: incidence ratios for each age group in the GP. ****SIR is standardized incidence ratio for the total, age-adjusted hospital admission rates between the GP and people with ID.

hospitalised more often than the GP. P values smaller than 0.05 were considered statistically significant. Standardised incidence ratio (SIR) was calculated to compare hospitalisation admission rates between people with ID and the GP. The statistical analyses were performed in SPSS and STATA.

Results Hospitalisations Among those hospitalised during this period, people with ID were hospitalised significantly more

frequently than the GP (P < 0.001). Based on population data from Statistics Norway and the assumption that the adult population with ID accounts for 0.45% of the GP, we found that during the study period of 2008–2011, on average 11% of people with ID and 11.5% in the GP were admitted to hospitals each year. A two-sample test of the proportions shows a statistically significant difference (P = 0.04). The analyses of each year separately showed statistically significant differences in hospital admission in people with ID and the GP for the years 2008, 2009 and 2010 but not for 2011 (results not shown).



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Length of an average hospital stay The average length of hospital stays among people with ID (aged 16–89 years) for each year of the 2008–2011 study period was 4.4, 4.4, 4.0 and 4.3 days, respectively. The average length of stay for the GP was 4.3 days in 2011 (Directorate of Health 2012, p. 7). Table 2 shows bed-days according to length of stay in 2011 for the age group 16–79: 13.4% of people with ID and 11.2% of the GP were hospitalised for 0 day in 2011 (i.e. outpatients). The analysis for ID and GP, performed separately, shows a relatively similar pattern of distribution for the lengths of hospital stays for the two groups. The majority of the stays for both groups lasted 1–5 days.

Hospitalisations according to age groups Within the age range of 16–89 years, the sample is divided into 5-year intervals. However, the oldest group contains a 10-year age span, 80–89 years, because there are relatively few people with ID in this age range (n = 271). Figure 1 shows the percentage of hospital admissions by age for people with ID and the GP. Among people with ID hospitalised during the 2008–2011 study period, there was a slightly higher proportion of admissions among those aged 35–60 years than for the other age groups. The proportion of admissions in these age groups was also slightly higher among those with ID compared with the age distribution of hospital admissions for the GP. Among people in the GP who were

hospitalised, 13.6% were in the age group 80–89 years, whereas the equivalent figure for people with ID was 3.6%. The SIR of 1.01 indicates that the total, age-adjusted hospital admission rates between the GP and people with ID are very similar. However, the incidence ratio for the different age groups indicates some age group differences, for instance in the following age groups: 16–29 (0.75), 40–49 (1.40), 50–59 (1.53) and 80–89 (0.36).

The 10 most common hospital admission diagnoses During the period of 2008–2011, hospitals registered 12 528 admissions for patients with ID (aged 16–79). In Table 4, they are presented together with the analysis of the hospital admissions for the GP in 2011. Among inpatients with ID, the most common diagnostic group (12.3%) included injury, poisoning and certain other consequences of external causes (S00–T98). In total, 37.4% of hospitalisations in injury, poisoning and certain other consequences of external causes (S00–T98) for people with ID were caused by fractures; 7.7% were caused by drug, medicaments and biological substances poisoning (T4n); and 6.0% by complications of orthopaedic devices, implants and grafts (T84). Circulatory system disease (I00–I99) was the second most common diagnostic group for hospitalisation for people with ID (10.7%) and the most common for the GP (13.7%). Angina pectoris

Figure 1 Hospital admissions by age group according to the distribution within each group among people with intellectual disability (ID) and the general population (GP) (2008–2011) in per cent. All numbers are from the NPR data.



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Table 4 List of the 10 most common ICD-10 diagnostic groups for inpatients with intellectual disability (ID) and the general population (GP) (persons 16–79 years old) at discharge

Inpatients with ID (2008–2011) Most common diagnostic groups XIX: S00–T98 Injury, poisoning and certain other consequences of external causes IX: I00–I99 Diseases of the circulatory system XI: K00–K93 Diseases of the digestive system XVIII: R00–R99 Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified X: J00–J99 Diseases of the respiratory system VI: G00–G99 Diseases of the nervous system XIV: N00–N99 Diseases of the genitourinary system XXI: Z00–Z99 Factors influencing health status and contact with health services II: C00–D48 Neoplasms XIII: M00–M99 Diseases of the musculoskeletal system and connective tissue (Sum) Other diagnoses Total

No

N

%

The general population (2011) No

N

%

1

1544

12.3

3

63 324

10.3

2 3 4

1344 1314 1281

10.7 10.5 10.2

1 8 5

84 068 46 022 52 703

13.7 7.5 8.6

5 6 7 8

1175 1135 830 610

9.4 9.1 6.6 4.9

9 6 10 2

39 436 50 292 34 294 68 547

6.4 8.2 5.6 11.1

9 10

570 564

4.5 4.5

4 7

62 276 46 909

10.1 7.6

(10 367) 2161 12 528

(82.7) 17.3 100.0

(547 871) 174 372 615 456

(89.0) 11.0 100.0

The numbers for the most common diagnostic groups for inpatients with ID are from the NPR data. The numbers for inpatients among the GP are retrieved from the NPR report generator (Norwegian Patient Register 2011).

(I20), chronic ischemic heart disease (I25), heart failure (I50) and acute myocardial infarction (I21) were common causes for both populations. The second most common cause for the GP (11.1%) included factors influencing health status and contact with health services (Z00–Z99). For people with ID, this group was the eighth most common cause for hospitalisation (4.9%). Diseases of the digestive system (K00–K93) were the third most common cause for admission for people with ID (10.5%) and the eighth for the GP (7.5%). Neoplasms (C00–D48) and diseases of the musculoskeletal system and connective tissue (M00–M99) were the 9th and 10th most common cause for admission for people with ID (both 4.5%). For the GP, neoplasms (10.1%) and muscle and skeletal diseases (7.6%) were more often registered at hospitals, number 4 and number 7, respectively. The most common single diagnostic code (not illustrated in Table 4) for hospital admission among people with ID include epilepsy (G40) and bacterial

pneumonia (J15). This correlates with findings from other countries (Glover & Evison 2013; Ailey et al. 2014). Unfortunately, we do not have access to similar figures for the GP.

Discussion Overall, the present analyses of data from different national registries in Norway indicate relatively similar patterns in hospitalisation among people with ID and the GP. During the period of 2008–2011, 11% of people with ID and 11.5% in the GP were hospitalised. The results are significantly different (P = 0.04), but the difference is small, and the practical implications of the statistical difference are uncertain. The results of this study is contrary to the results of studies from several other countries, finding that adults with ID are hospitalised more often and have longer admissions than the GP (Balogh et al. 2010; Tennenbaum et al. 2011; Glover & Evison 2013; Zhu et al. 2013; Ailey et al. 2015). Balogh et al. (2010)



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discuss whether the different hospitalisation rates in developed countries after de-institutionalisation are associated with variations in national health care systems. In England and the Netherlands, multidisciplinary outpatient teams were able to effectively decrease hospitalisations for people with ID with a co-morbid mental health condition (Van Minnen et al. 1997; Hassiotis et al. 2001). In Norway, the habilitation service offers multidisciplinary inpatient and outpatient services for people with ID. The present study uses data on somatic care and inpatient treatment. We do not have access to data on mental health care, whereas half of the habilitation services are organised under psychiatric care. In May 2015, the habilitation service launched activity data for the first time (Norwegian Directorate of Health 2015). The report shows that many adult people with ID are examined and treated for common diseases or ailments in the habilitation service as outpatients. This might be one explanation why they are not referred to the general somatic hospital wards as often as in other countries. In addition, the most common reason for contact with the service is mental and behavioural disorders (F00–F99), accounting for 53% of all referrals, both for inpatient and outpatient service, but mostly for outpatient consultations (Norwegian Directorate of Health 2015, p. 19). Another, plausible explanation may be that the health monitoring of people with ID is insufficient. Studies on self-reported health of people with ID describe their limited abilities for self-report (Fujiura, G., & the RRTC Expert Panel on Health Measurement (E. Andresen, B. Cardinal, C. Drum, T. Hall, W. Horner-Johnson, G. Krahn, M. Nosek, Jana Peterson-Besse, & R. Suzuki) 2012; Burke et al. 2014, p. 83). We assume that the lack of ability to selfreport health, together with diagnostic overshadowing by caretakers or clinicians overlooking symptoms of health problems and attributing them to ID, may be another contributing factor. This is documented in the 2007 report entitled Health Monitoring of People with Intellectual Disabilities (2007). In this study, the average length of hospital stay was 4.3 days for people with ID and for the GP. Studies from other countries report mostly longer hospitalisations among people with ID compared with the GP (Balogh et al. 2010; Tennenbaum et al. 2011;

Glover & Evison 2013; Zhu et al. 2013; Ailey et al. 2015). In England, Glover & Evison (2013) found an average admission of 5.8 days for people with ID compared with 3.7 days for the GP. They also found that emergency admissions last even longer for people with ID. Exceptionally long hospitalisations were seen for patients with DS at the departments of internal medicine, dermatology and intensive care units (Tennenbaum et al. 2011). Researchers from Denmark investigated the hospitalisation of people with DS for the period from 1977 to 2008, finding more than twice the rate of hospital admissions and nearly three times as many bed-days as for the GP as a whole (Zhu et al. 2013). Ailey et al. (2015) reported several complications among adult people with ID hospitalised at an Academic Medical Center. People with ID tend to be twice as likely to have complications if they had a surgical procedure and nearly four times as likely to have complications if they had multiple chronic health conditions compared with the GP. People with ID who are hospitalised in Norway may be discharged faster than, for instance, people in the GP who live alone and are considered frail. Because most people with ID live in group homes or equivalent housing that includes caretakers, disability nurses and sometimes registered nurses, we believe that they are discharged as soon as possible. Health care workers at hospitals may assist by pre-ordering help needed in the municipality for an earlier discharge (e.g. home nursing, physiotherapy). The Norwegian Coordination Reform in Health Care implemented in 2012 is a contract between the primary health care sector and the specialised health care sector. The primary health care sector receives financial support as incentive to treat patients in the municipality. As a consequence, patients are discharged earlier from hospitals to primary care than before the reform (Norwegian ministry of health and care services 2012). We also found some age group differences in our study. Hospitalisations are more frequent for people with ID compared with the GP in the 40–59 age groups and less frequent in the 16–29 and 80–89 age groups, as shown in Fig. 1 and Table 3. In the GP, hospitalisation is most common among the oldest, whereas among people with ID, the age group between 35 and 60 years top the hospitalisation statistics, but this trend decreases after age 65 (Fig. 1).



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The number of people estimated to have ID in the oldest age groups in Table 3 (60 years of age and older) is probably in the high end, and estimations for the oldest age groups are the least robust, but the present results are in accordance with findings from Canada and England (Balogh et al. 2010; Glover & Evison 2013, p. 13). Just a few decades ago, it was more common for people with mild ID to be institutionalised and receive benefits because of their disability. Hence, the oldest age groups with ID may be more likely to include people with mild ID than the younger age groups. Moreover, it is likely that people with ID who reach an advanced age are in better general health than those who do not survive to old age and therefore have limited need for medical care at hospitals. The Canadians shared the same assumptions and discussed the ‘healthy survivor’ effect (Balogh et al. 2010). However, the same hypothesis may also apply for the GP. We suspect that the low hospital admission rates among the oldest patients with a known ID may be because of other factors as well, such as under-diagnosis, which is a common problem because of their limited ability to express complaints or cooperate in physical examinations (Lennox et al. 1997). The Health Monitoring of People with Intellectual Disabilities (2007, p. 44) report stated that there are still major challenges in the specialist health care service to accommodate the special needs for people with ID. Caretakers may, for several different reasons, choose to care for some of the oldest patients in their homes. In Norway, the habilitation service offers home visits, probably more often than registered (Norwegian Directorate of Health 2015). The high rates of hospitalisation for people with ID aged 35–60 years could potentially be linked to their frailty and early onset of the ageing process. Adults with ID show more signs of early frailty than the GP (Schoufour et al. 2013). Results from the ‘Dutch Healthy Ageing and Intellectual Disability Study’ show that, between ages 50 and 64, frailty is as prevalent as in the GP aged 65 and older, with a further increase after the age of 65 (Evenhuis et al. 2012). Evenhuis et al. discussed how ID predisposes people to premature ageing, which is generally accepted among professionals working in the ID field. There is an increased age-related

vulnerability in this population, but its character is unclear and merits further investigation (Evenhuis et al. 2012). The habilitation service reports that people with ID between 19 and 39 years old account for almost 73% of all outpatient activity. Patients in the oldest age groups receive habilitation services to a lesser degree, and it is mostly the youngest of the adults with ID who get necessary medical care (Norwegian Directorate of Health 2015, p. 15). Injury, poisoning and certain other consequences of external causes (S00–T98) represent the most common cause for hospital admissions for people with ID (12.3%). This diagnostic group is the third most common cause (10.3%) among patients in the GP (Norwegian Patient Register 2011) and the second most common cause in another Norwegian survey (2007–2008) that examined acute hospital admissions in nursing homes (Graverholt et al. 2013). People with ID seem to be susceptible to fractures just as elderly people in nursing homes. Falls are a major issue for people with ID because of problems such as medication side effects, epilepsy, poor balance and poor motor skills (Smulders et al. 2013; Cahill et al. 2014). Osteoporosis, or low bone density, may be the cause of fractures in people with ID, who are at greater risk for developing osteoporosis because of their inactivity, low levels of sunlight exposure (vitamin D) and frequent use of anticonvulsant drugs (Haveman et al. 2010; Burke et al. 2014; Frighi et al. 2014). Having DS, Rett syndrome, Turner syndrome or Prader–Willi syndrome is another risk factor because of hypogonadism and reduced growth (Bakalov et al. 2006; Zysman et al. 2006; Prader-Willi Syndrome Association, 2008; Petrone 2012). While we lack information regarding osteoporosis in people with ID, research shows that Norway has a high incidence of fractures – especially of the hip, spine and wrist – caused by a high prevalence of osteoporosis in the general elderly population (The Norwegian Institute of Public Health 2014b). Studies from other countries report that adults with ID develop osteoporosis more frequently than adults in the GP (Jasien et al. 2012; Burke et al. 2014). In addition to the tendency to develop osteoporosis and low bone density, people with ID also have idiopathic fractures (Jasien et al. 2012). To our knowledge, very few measures to prevent falls are in use for people



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with ID in Norway. This is also reflected in a Dutch study (de Jonge & Tonino 2009). People with ID often use several medications to treat their chronic medical conditions, which put them at greater risk for polypharmacy (Bygdnes & Kristiansen 2007; O’Dwyer et al. 2013). A US survey analysing hospitalisation among people with ID showed similar results. Their study was based on a state-wide hospital database, and the most common admission diagnoses for people with ID were falls and drug poisoning (Wang et al. 2002). One might wonder why people with ID are rarely hospitalised for diseases of the musculoskeletal system and connective tissue (M00–M99). This group includes a variety of bone density and structural disorders, and we might speculate that osteoporosis is under-diagnosed. This is the 10th most common diagnostic group for people with ID (4.5%). Most people who seek treatment for musculoskeletal disorders report pain from several areas (Ihlebæk et al. 2010). Dealing with pain is a challenging task for most people, and people with ID face barriers addressing pain because some cannot provide valid self-reports. Like the figures from those hospitalised, the habilitation service reports only a few referrals concerning diseases of the musculoskeletal system and connective tissue (Norwegian Directorate of Health 2015). Circulatory system disease (I00–I99) is the second most common cause for hospital admission for people with ID (10.7%) and the most common cause for the GP (13.7%). Obesity, smoking, low levels of physical activity and diabetes increase the risk of cardiovascular diseases (CVDs), which are common in adults with ID because of their consumption of fatty foods, low levels of physical activity and a tendency to suffer from type 2 diabetes (Melville, Hamilton, Hankey, Miller, & Boyle, 2007; McCarron et al. 2011; Burke et al. 2014). A recent Norwegian study on health issues in people with DS, Prader–Willi syndrome, and Williams syndrome reported that 78% are overweight or obese (Nordstrøm et al. 2013). Over the past decades, mortality from CVD in the Norwegian population has decreased, but the number of elderly living with the condition is rising (Statistics Norway, 2011). People with low education levels and low incomes suffer from ailments such as CVD,

diabetes and pain more frequently than people with higher incomes and education levels (Norwegian Institute of Public Health, 2007). Preventive health care over the years, like the Tobacco Act in Norway, is slowly beginning to yield results in the GP among those who are well educated, but public health education has rarely been adapted to people with ID. Digestive system disease (K00–K93) is the third most common cause for admission to hospitals for people with ID (10.5%) and the eighth for the GP (7.5%). Gastroesophageal reflux disease (GERD) and constipation are major clinical problems among people with ID. GERD and other gastrointestinal disorders are more common in adults with ID compared with the GP (Evenhuis et al. 2001; Morad et al. 2007; Haveman et al. 2010; Burke et al. 2014). Stomach and intestinal disorders are rarely highlighted as a major general health problem among the GP in Norway, but the disorders increase with normal ageing (The Norwegian Institute of Public Health 2014a). The second most common cause for hospital admission among patients in the GP (11.1%) is factors influencing health status and contact with health services (Z00–Z99). (74–76) This is the eight most common admisson diagnostic group for people with ID (4.9%). It should be noted that the ICD-10 cautions against using this chapter for international comparison, because this diagnostic group does not include diseases or injuries but issues such as encountering health services for examination and investigation or potential health hazards related to socioeconomic and psychosocial circumstances or communicable diseases (WHO 2010). It appears that people with ID may be admitted to the hospital less frequently for factors influencing health status despite their frailty. This assumption is supported by other research (Davis et al. 2014). An interesting piece of information from the habilitation report is that the second most common cause for referral is factors influencing health status and contact with health services (Z00–Z99), constituting 22%. During 2013, 7122 patients (from 19 to 80 years) were referred to the habilitation service and they received 36 191 outpatient consultations (Norwegian Directorate of Health 2015, p.14 and p. 19 and 21). Cancer is a major health concern in Norway (Cancer Registry of Norway 2011). The most common cancer diagnoses are mostly the same for



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adults with ID and the GP, but admissions because of a cancer diagnosis are registered more than twice as often among the GP (10.1%) compared with people with ID. In accordance with our findings, a Danish study found that hospitalisations for neoplasms and diseases of the musculoskeletal system or connective tissue were less frequent among adults with DS compared with the GP (Zhu et al. 2013). Our study found that neoplasms (C00–D48) were relatively rare in people with ID, constituting the ninth most common cause for admission diagnostic group (4.5%). This disparity leads to further questions regarding whether many cancers go unrecognised and undiagnosed in people with ID. The incidence of new cancer cases in people with ID is unknown, but it may be presumed that the cancer risk is equal for people with mild and moderate ID and the GP (Patja et al. 2001; Sullivan et al. 2004; Satgé et al. 2007). Because the likelihood of cancer increases with age, we might expect more cases in the future, also among people with ID.

Strengths and limitations We do not have information on diagnoses or levels of ID of the individuals included in this sample, and our findings have limited generalisability because the adult people with ID who are registered in the NAV registry are estimated to cover less than 30% of the total population of people living with ID in Norway. The strength of the present study is that it is based on high-quality registry data, including a large sample size. Internationally, there are only a few studies on hospitalisation among people with ID, and this is the first conducted in Norway. The present data set includes a limited number of variables, which means that analyses of associations and interpretations about causality are precluded. However, the results may guide policymaking and shed light on issues that need further investigation.

Conclusion The objective of this study was to describe hospitalisation for administratively defined people with ID compared with the GP in Norway. Our results show that the proportion of people being hospitalised each year is almost the same among adults with ID and the GP. Most people admitted to a hospital were admitted only one time, but the estimates indicate that people with ID admitted to

hospital are admitted slightly more often than the GP. The length of an average hospital stay for both the GP and people with ID was 4.3 days. Opposed to the distribution in the GP, people with ID are hospitalised more frequently in the younger age groups and less frequently among the oldest. The most common reasons for hospital admissions for people with ID are injury, poisoning and certain other consequences of external causes, diseases of the circulatory system and diseases of the digestive system. Cancer and musculoskeletal diseases are notably less often the cause of admission for people with ID compared with the GP. The newly released report from the habilitation service showed that adults with ID are often examined and treated in the habilitation service, mostly as outpatients. The present study only included inpatient treatment. Unfortunately, there is no register for the activity in the primary health care service (Norwegian Directorate of Health 2015, p. 5) that could have provided additional information on whether adults with ID are examined and treated in the municipality instead of being admitted to the specialised health care service. The findings of this study underscore that further investigations are crucial to determine whether particularly elderly people with ID are receiving the necessary health care in Norway and around the world.

Acknowledgements We would like to thank the Norwegian Patient Register (NPR) and Norwegian Labour and Welfare Service (NAV) for the data extradition and counselling during the process of completing this paper. We would also like to thank our colleagues at the Norwegian National Advisory Unit on Ageing and Health for professional inputs and support. A special thanks goes to Øyvind Kirkevold, Frode Kibsgaard Larsen, Bjørn Heine Strand, Bo Terning Hansen and our librarians Vigdis Knutsen and Katarina Einarsen Enne.

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Accepted 2 December 2015


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