Higher incidence of hip fracture in newly diagnosed schizophrenic patients in Taiwan

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Date 2013/March/22

Type of manuscript: letter to editor

 Manuscript title：Higher Incidence of Hip Fracture in newly diagnosed Schizophrenic patients in Taiwan

 Running head：schizophrenia and hip fracture

 Authors' full names:

 Shih-Wei Lai1,2_{, Cheng-Li Lin}3,4_{, Kuan-Fu Liao}5,6,7



 1_{School of Medicine,}3_{Department of Public Health, and} 5_{Graduate Institute of}

Integrated Medicine, China Medical University, Taichung, Taiwan

 2_{Department of Family Medicine and}4_{Management Office for Health Data,}

China Medical University Hospital, Taichung, Taiwan

 6_{Department of Internal Medicine, Taichung Tzu Chi General Hospital,}

Taichung, Taiwan

 7_{Department of Health Care Administration, Central Taiwan University of}

Science and Technology, Taichung, Taiwan

 Corresponding author: Kuan-Fu Liao, MD and MS

Department of Internal Medicine, Taichung Tzu Chi General Hospital, No.66, Sec. 1, Fongsing Road, Tanzi District, Taichung City, 427, Taiwan

Phone: 886-4-2205-2121 Fax: 886-4-2203-3986

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Abstract

Objectives. This study was to clarify the relationship between schizophrenia and risk of hip fracture in older people in Taiwan.

Methods. We used the database from the Taiwan National Health Insurance program to conduct this cohort study. We randomly selected 445 subjects aged 65 years or older with newly diagnosed schizophrenia as the case group (mean age [standard deviation] = 75.2 [6.9] years) and 1780 subjects aged 65 years or older without schizophrenia as the comparison group (mean age [standard deviation] = 74.2 [7.1] years), from 2000 to 2010. We measured the incidence of hip fracture.

Results. The schizophrenia group had a significantly higher incidence of hip fracture than the non-schizophrenia group did (20.3 vs. 10.6 per 1000 person-years, incidence rate ratio [IRR] = 1.91, 95% CI= 1.49-2.44).

Conclusions. Older people with schizophrenia have a 1.9-fold increased risk of hip fracture in Taiwan.

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Hip fracture is a major public health concern due to its poor outcome and serious socioeconomic burden in older people.(1) The evidence has shown many factors are related to increased risk of hip fracture, but psychiatric diseases not confirmatory.(2-3) A case-control study by Howard et al in the UK has shown that schizophrenia is associated with increased risk of hip fracture in univariate analysis (odds ratio [OR] = 1.73, 95% CI= 1.32-2.28), but no longer association is found in multivariate analysis. (3)

To date, no clinical study is to focus on the relationship between schizophrenia and risk of hip fracture in older people in Taiwan. In order to clarify this issue, we used the database from the Taiwan National Health Insurance program to conduct this population-based cohort study. The details of insurance program can be found in previous studies.(4-6)

In this study, we randomly selected 445 subjects aged 65 years or older with newly diagnosed schizophrenia as the case group by the diagnosis codes of the International Classification of Diseases 9th_{Revision-Clinical Modification (ICD-9 codes 295 and}

V11.0, 210 men and 235 women, mean age [standard deviation] = 75.2 [6.9] years) and 1780 subjects aged 65 years or older without schizophrenia as the comparison group (840 men and 940 women, mean age [standard deviation] = 74.2 [7.1] years), from 2000 to 2010. Both groups were matched for gender, age and diagnosing year of schizophrenia. We measured the incidence of hip fracture (ICD-9 codes 820) until hip

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schizophrenia group than that in the non-schizophrenia group, with statistical significance. Men with schizophrenia had a higher risk of hip fracture than women with schizophrenia did (IRR 3.26 vs. 1.42). Subjects with schizophrenia aged 75-84 had the highest incidence than other sub-groups did (incidence rate =35.4 per 1000 person-years), but subjects with schizophrenia aged 65–74 had a higher risk of hip fracture (IRR= 2.14, 95% CI = 1.51-3.02). The risk of hip fracture was higher among subjects with duration of diagnosing schizophrenia less than 2 years (IRR= 2.82, 95% CI = 2.16-3.69), as compared to those with duration ≥ 2 years (IRR= 1.54, 95% CI = 1.14-2.07) (Table 1).

A case-control study by Bolton et al in Canada has shown that schizophrenia is associated with increased risk of osteoporotic fractures after adjusted for covariates (OR = 1.61, 95% CI= 1.27-2.04), but not focusing on hip fracture.(7) In this present study, patients with schizophrenia have a 1.9-fold increased risk of hip fracture. In further analysis, we also found that the risk of hip fracture is 2.8-fold in patients with duration of diagnosing schizophrenia less than 2 years, as compared with subjects without schizophrenia. This means that more efforts should be made to prevent falls in older people with schizophrenia, particularly in the first 2 years of diagnosing schizophrenia. Due to inconsistent results from above studies, additional studies are needed to determine the relation of schizophrenia and hip fracture in older people.

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Funding

This study was supported in part by Taiwan Department of Health Clinical Trial and Research Center of Excellence (DOH102-TD-B-111-004).The funding agency did not influence the study design, data collection and analysis, decision to publish, or

preparation of the manuscript.

Conflict of Interest Statement: The authors disclose no conflicts of

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References

1. Wehren LE,Magaziner J: Hip fracture: risk factors and outcomes. Curr Osteoporos Rep 2003; 1:78-85

2. Beer C,Giles E: Hip fracture--challenges in prevention and management. Aust Fam Physician 2005; 34:673-676

3. Howard L, Kirkwood G,Leese M: Risk of hip fracture in patients with a history of schizophrenia. Br J Psychiatry 2007; 190:129-134

4. Lai SW, Liao KF, Liao CC, et al: Polypharmacy correlates with increased risk for hip fracture in the elderly: a population-based study. Medicine (Baltimore) 2010; 89:295-299

5. Lai SW, Su LT, Lin CH, et al: Polypharmacy increases the risk of Parkinson's disease in older people in Taiwan: a population-based study. Psychogeriatrics 2011; 11:150-156

6. Lai SW, Lin CH, Liao KF, et al: Association between polypharmacy and dementia in older people: a population-based case-control study in Taiwan. Geriatr Gerontol Int 2012; 12:491-498

7. Bolton JM, Metge C, Lix L, et al: Fracture risk from psychotropic medications: a population-based analysis. J Clin Psychopharmacol 2008; 28:384-391

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Table 1. Incidence rates of hip fracture for schizophrenia group and non-schizophrenia group Non-schizophrenia Schizophrenia N Case Person-years Incidence Rate N Case Person-years Incidence rate

Incidence rate ratio (95% CI) †

All 1780 113 10640 10.6 445 42 2072 20.3 1.91(1.49, 2.44)

gender

men 840 30 4770 6.29 210 17 830 20.5 3.26(2.27, 4.67)

women 940 83 5870 14.1 235 25 1242 20.1 1.42(1.02, 1.99)

Age group (year)

65–74 956 37 6611 5.60 239 16 1338 12.0 2.14(1.51, 3.02)

75-84 824 76 4029 18.9 206 26 734 35.4 1.88(1.34, 2.64)

Follow-up period

< 2 years 340 29 3232 8.97 130 19 751 25.3 2.82(2.16, 3.69)

≥ 2 years 1440 84 7408 11.3 315 23 1321 17.4 1.54(1.14, 2.07)

Incidence rate: per 1000 person-years