Impact of comorbidity, age, and gender on seasonal variation in hip fracture incidence. A NOREPOS study
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Based on a total of 136,140 hip fractures, we found a distinct seasonal variation in hip fracture incidence present in subgroups defined by age, gender, and comorbidity. The seasonal variation was most pronounced in the youngest and the healthiest patients.
The purpose of this study was to examine the possible seasonal variation in hip fracture incidence in Norway by comorbidity, age, and gender.
Data were retrieved from the NOREPOS Hip Fracture Database containing all hip fractures in Norway during the time period 1994–2008. Hip fractures were identified by computerized hospital discharge diagnoses. Charlson comorbidity index was calculated based on additional diagnoses and categorized (0, 1, and ≥2). Summer was defined as June, July, and August and winter as December, January, and February. Incidence rate ratios for hip fracture according to season were calculated by negative binomial models.
In patients aged 50–103 years, 136,140 eligible fractures were identified (72.5 % women). The relative risk of hip fracture in winter versus summer was 1.40 (95 % confidence interval (CI) 1.36–1.45) in men and 1.26 (95 % CI 1.23–1.28) in women. June had the lowest number of fractures in both genders. We found seasonal variation in all subgroups by age and gender, although least pronounced in patients >79 years. There was a significant interaction between season and comorbidity (p = 0.022). When comparing winter to summer, we found relative risks of 1.40 (95 % CI 1.31–1.50) in patients with Charlson index = 0, 1.29 (95 % CI 1.19–1.40) in patients with Charlson index = 1, and 1.18 (95 % CI 1.08–1.28) in patients with Charlson index ≥2.
There was a distinct seasonal variation in hip fracture incidence, present in all subgroups of gender, age, or comorbidity. This variation should be accounted for when planning health-care services.
KeywordsHip fracture Incidence Seasonal variation Comorbidity Age Gender
Conflict of interest
- 1.Kanis JA, Oden A, McCloskey EV, Johansson H, Wahl DA, Cooper C, Epidemiology IOFWGo, Quality of L (2012) A systematic review of hip fracture incidence and probability of fracture worldwide. Osteoporos Int: J Established Res Coop Eur Found Osteoporos Natl Osteoporos Found USA 23(9):2239–2256Google Scholar
- 18.Emaus N, Olsen LR, Ahmed LA, Balteskard L, Jacobsen BK, Magnus T, Ytterstad B (2011) Hip fractures in a city in Northern Norway over 15 years: time trends, seasonal variation and mortality: the Harstad Injury Prevention Study. Osteoporos Int: J Established Res Coop Eur Found Osteoporos Natl Osteoporos Found USA 22:2603–2610CrossRefGoogle Scholar
- 22.Stagg V (2006) CHARLSON: Stata module to calculate Charlson index of comorbidity. http://ideas.repec.org/c/boc/bocode/s456719.html#download. Accessed January 14th 2014
- 24.(2013) Table: 07459: Population, by sex and one-year age groups. Statistics Norway, https://www.ssb.no/statistikkbanken/selectvarval/Define.asp?subjectcode=&ProductId=&MainTable=NY3026&nvl=&PLanguage=1&nyTmpVar=true&CMSSubjectArea=befolkning&KortNavnWeb=folkemengde&StatVariant=&checked=true. Accessed January 7th 2014
- 25.Ismail N, Jemain AA (2007) Handling overdispersion with negative binomial and generalized Poisson regression models. Casualty Actuarial Society ForumGoogle Scholar
- 30.Nurmi I, Kaukonen JP, Luthje P, Naboulsi H, Tanninen S, Kataja M, Kallio ML, Leppilampi M (2005) Half of the patients with an acute hip fracture suffer from hypovitaminosis D: a prospective study in southeastern Finland. Osteoporos Int: J Established Res Coop Eur Found Osteoporos Natl Osteoporos Found USA 16:2018–2024CrossRefGoogle Scholar
- 31.Pasco JA, Henry MJ, Kotowicz MA, Sanders KM, Seeman E, Pasco JR, Schneider HG, Nicholson GC (2004) Seasonal periodicity of serum vitamin D and parathyroid hormone, bone resorption, and fractures: the Geelong Osteoporosis Study. J Bone Min Res : Off J Am Soc Bone Min Res 19:752–758CrossRefGoogle Scholar
- 32.Midtby M, Magnus JH, Joakimsen RM (2001) The Tromso Study: a population-based study on the variation in bone formation markers with age, gender, anthropometry and season in both men and women. Osteoporos Int: J Established Res Coop Eur Found Osteoporos Natl Osteoporos Found USA 12:835–843CrossRefGoogle Scholar