Risk of motor vehicle accidents with profound injuries in patients with ankylosing spondylitis: a nationwide, population-based cohort study

Abstract

Background: Patients with ankylosing spondylitis (AS) suffer from impaired physical activity and are prone to motor vehicle accidents (MVA), but definite instruction regarding the relationship between disease evolvement and MVA and potential risk factors is lacking.

Objectives: To explore the risk factors and their impact on recorded MVA with profound injuries in AS patients with prescriptions.

Design: Nationwide, population-based, matched retrospective cohort study.

Methods: Using Taiwanese administrative healthcare databases, with available claims data from 2003 to 2013, we selected 30,911 newly diagnosed adult AS patients with concurrent prescriptions from 2006 to 2012 as AS patients, along with 309,110 non-AS individuals as the control group, matched in gender, age at index date and year of the index date. The risk of recorded MVA with profound injuries was compared between the two groups in terms of incidence rate ratio (IRR) and log-rank test p-value. Using Cox regression analysis, we studied associations between the risk and AS diagnosis.

Results: The risk of recorded MVA with profound injuries in AS patients was significantly higher than in non-AS individuals, specifically 2 years after AS diagnosis (IRR, 2.00; 95% confidence interval (CI), 1.42-2.81). For patients with follow-up periods >2 years, the adjusted risk was positively associated with suburban residence (adjusted hazard ratio (aHR), 2.18; 95% CI, 1.55-3.06), rural residence (aHR, 1.89; 95% CI, 1.27-2.80), lower insured income (aHR, 1.35; 95% CI, 1.01-1.81) and recorded MVA with profound injuries before AS diagnosis (aHR, 6.16; 95% CI, 2.53-14.96). AS diagnosis (aHR, 1.81; 95% CI, 1.27-2.59) and frequency of ambulatory visits (aHR, 1.01; 95% CI, 1.004--1.02) were specific associated factors for them compared with those with follow-up periods ⩽2 years.

Conclusion: For adult AS patients in Taiwan, factors such as AS disease evolution and frequent ambulatory visits for disease control in the second year of the disease course may significantly increase the risk of recorded MVA with profound injuries beyond 2 years after AS diagnosis.

Keywords: ankylosing spondylitis; claims data; cohort study; health-related quality of life; motor vehicle accident; population-based study.

Figure 1.

Flow diagram of enrolment, categorisation and matching for comparison of the study population. AS, ankylosing spondylitis; LHID, Longitudinal Health Insurance Database; NHIRD, National Health Insurance Research Database; OPD, outpatient department.

Figure 2.

Kaplan–Meier curves of cumulative incidence of motor vehicle accidents with profound injuries among matched study subjects. (a) During the entire follow-up period. (b) Period within 2 years after the index date. (c) Period beyond 2 years after the index date.