The Norwegian Hip Fracture Register

This is a population-based (5.3 million inhabitants in 2018) national prospective study based on data from the NHFR. The term "hip fracture" denotes patients with femoral neck fractures (FNFs: ICD10 code S72.0), trochanteric (ICD10 code S72.1) and subtrochanteric (ICD10 code S72.2) fractures. The NHFR has collected data on all hip fracture patients admitted to hospitals in Norway since 2005. The NHFR receives a form with information on patients, primary operations, and subsequent reoperations. Information on patients receiving total hip arthroplasty (THA) is primarily registered in the Norwegian Arthroplasty Register (NAR) and subsequently imported to the NHFR.¹⁰

Completeness of reporting to the NHFR is evaluated regularly by comparing registry data with the national administrative database (Norwegian Patient Registry) operated by the Norwegian Directorate of Health. Completeness in 2015 to 2016 was 88.2% for osteosynthesis, 94.5% for hemiarthroplasties, and 87.8% for total hip arthroplasties.⁴

Data from all patients registered with a hip fracture in the NHFR in the five-year period (January 2014 to December 2018) admitted to all 43 hospitals in Norway routinely treating hip fractures were included. Data on patient characteristics (age, sex, American Society of Anesthesiologists grade¹¹ ), fracture type, and treatment information (time from injury to surgery, type of treatment, experience level of the surgeon, and reoperations) were extracted. Information on time from injury to operation, fracture type, and experience level of the surgeon were unavailable for hip fracture patients treated with THA, since this is not recorded in the NAR.

Follow-up

The patients were followed in the NHFR until time of reoperation. Patients without reoperations were censored at time of death or on 31 December 2019. Data on death was provided to NHFR by the Norwegian National Population Register.

Characteristics of Norwegian acute care hospitals/hospital trusts

We performed an online survey of the characteristics of all 43 hospitals (23 hospital trusts) in Norway that routinely treat hip fracture patients. The hospitals varied from small community hospitals with a catchment area of fewer than 30,000 inhabitants to large regional and university hospitals.¹² Information was collected on the organization of hip fracture care, presence of hospital treatment policies/guidelines, dedicated unit for hip fracture patients, interdisciplinary care including an orthogeriatric unit, number of beds in the orthopaedic ward(s), number of orthopaedic consultants and specialist registrars/residents, and whether the hospital had 24/7 service for hip fracture patients. We ranked the hospitals by treatment volume (low to high) and then divided them into four volume groups with an equal number of hospitals in each group.

Evidence-based hip fracture guidelines

Guidelines were identified from the Guidelines International Network (GIN),¹³ using the search terms “hip fracture” and “hip fracture treatment”. We also searched for evidence-based guidelines in BMJ Best Practice and PubMed. We identified six relevant guidelines of high quality. We excluded a Finnish and a German guideline published in their respective native languages. We also added a consensus-based Norwegian guideline.^5,14

From international guidelines^6-9 we extracted treatment recommendations. They largely coincide with the Norwegian interdisciplinary guideline, which is based on the critical literature review and evidence base published by National Institute for Health and Care Excellence (NICE) in the UK.⁹ Three of the five guidelines (American Academy of Orthopaedic Surgeons (AAOS), Scottish Intercollegiate Guidelines Network (SIGN), Norwegian Orthopaedic Association (NOF)) address hip fracture treatment in the elderly. The guideline recommendations are summarized in Table I, which also outlines treatment-related and outcome variables where the NHFR could provide information. Guideline summaries were extracted by two experienced orthopaedic surgeons (CK, J-EG).

Recommendations independent of type of fracture included data on the time of treatment within 48 hours after injury and on surgeon competence, in the NHFR defined as more than three years of experience with fracture surgery. Fracture type-dependent treatment recommendations included treatment of undisplaced (Garden types 1 and 2¹⁵) femoral neck fractures (FNFs) with screw fixation (two or three screws or pins), treatment of displaced FNFs (Garden types 3 and 4) with arthroplasty (hemi- or total hip arthroplasty) and use of a cemented stem.

For trochanteric fractures type AO/Orthopaedic Trauma Association (AO/OTA) A1,¹⁶ the guidelines recommend a sliding hip screw (SHS) rather than an intramedullary nail (IMN). For intertrochanteric fractures, type AO/OTA A3, and subtrochanteric fractures, the guidelines recommend IMN. For trochanteric fractures, type AO/OTA A2, there is equipoise between SHS and IMN. These fractures were therefore not included in the analysis.

We estimated the proportion of patients receiving treatment fulfilling the guideline recommendations described in Table I, i.e. treatment within 48 hours; y a surgeon with more than three years’ of experience; and using fracture-specific recommended treatment. This composite best practice indicator, reflecting and summarizing adherence to guideline recommendations, was calculated for each fracture-specific group. We also estimated best practice for all hip fractures as a group, i.e. practice that fulfilled the guideline criteria for all fracture types.

The NHFR contained data on 41,699 patients treated for a hip fracture in the five-year period between January 2014 and December 2018 (Figure 1). We excluded in sequential order patients with pathological fractures (treatment based on surgeon discretion), patients younger than 65 years (the focus was on elderly patients), patients with ASA grade 5 (moribund patients at operation), or with missing information on ASA grade. Similarly, patients with fracture types with equal recommendations in the guidelines (basocervical fractures and multifragmented trochanteric fractures, type AO/OTA A2), combined fracture types and those in whom fracture type was missing were excluded. Subsequently, 29,613 patients were included in the study: 21,325 FNF, 5,546 trochanteric and 2,742 sub- or intertrochanteric fractures (Figure 1). We included 20,427 women and 9,186 men, with median age 84 years (interquartile range (IQR) 78 to 89) and 83 years (IQR 75 to 88) respectively. Patient characteristics and fracture types are outlined in Table II.

Fig. 1

Patient selection-study population. OTA, Orthopaedic Trauma Association; ASA, American Society of Anesthesiologists.

Statistical analysis

The analysis was performed using SAS/STAT for Windows v. 7.1 (SAS Institute, Cary, North Carolina, USA). Continuous variables are presented as medians and ranges for patients and hospital characteristics. Treatment distribution is presented in numbers and percentages. Adherence to guideline recommendations was calculated as a mean of annual proportions of patients treated according to the recommendations described. This was performed for each hospital over the study period and adjusted for age and sex. We used logistic regression (LR) models to measure the effect of the predictors of adherence and results are presented as odds ratios (ORs). All analyses were adjusted for age, sex, and ASA class. For all LR analyses, a 95% confidence interval (CI) was calculated and p-values below 0.05 were considered statistically significant.

Ethics, funding and conflict of interest

The project was approved by the Northern Norway Regional Committee for Medical and Health Research Ethics and was exempted from the duty of confidentiality (REK 2018/1955). A data protection integrity assessment was compiled according to the EU General Data Protection Regulation (GDPR). The project was funded by the Northern Norway Regional Health Authority (HNF1482-19). No competing interests were declared.

The NHFR is authorized by the Norwegian Data Protection Authority to collect and store data on hip fracture patients (authorisation issued 3 January 2005; reference number 2004/1658 to 2 SVE/-). The NHFR required patients to sign a written, informed consent declaration, and when unable to understand or sign, a family member could sign the consent form on their behalf. The NHFR is financed by the Western Norway Regional Health Authority.

Patient and treatment characteristics

Overall, two-thirds of the patients had severe comorbidity (ASA class 3 to 4; n = 19,682). A majority of the patients were treated within 48 hours of injury and by an experienced surgeon (79%; n = 23,390). FNFs were most prevalent (72%; n = 21,325). Fracture treatment is outlined in Table III. Most (86%; n = 3,747) undisplaced FNFs were treated with screw fixation, whereas almost all (96%; n = 16,219) displaced FNFs were treated with arthroplasty. In all, 68% of trochanteric fractures received SHS (n = 3783) while IMN was used in 76% (n = 2,084) of inter- and subtrochanteric fractures.

Hospital characteristics

Treatment volume and organization of orthopaedic services are given in Table IV. The majority of hospitals (74%; n = 32)) reported having a separate orthopaedic ward, a hospital hip fracture programme (86%; n = 37)) and 24/7 service for hip fracture patients (86%; n = 37)). A dedicated hip fracture unit was present in 26% of the hospitals (n = 11), while an orthogeriatric service was present in 33% (n = 14). The hospitals had a median of seven orthopaedic consultants (IQR 5 to 17) and seven specialist registrars/residents (IQR 3 to 9) in orthopaedic surgery. In the study period, the median hospital patient volume was 553 (IQR 309 to 892).

Hospital adherence to guidelines

Variation in adherence to guideline recommendations (described in Table I) related to hospital category (volume groups) has also been estimated and is illustrated in Figure 2.

Fig. 2

a) Surgery within 48 hours. b) Surgeon with more than three years of fracture surgery experience. c) Undisplaced femoral neck fractures (FNFs) treated with screw fixation. d) Displaced FNFs treated with arthroplasty. e) Arthroplasties with cemented stem. f) Trochanteric AO/OTA A1 fractures treated with sliding hip screw (SHS). g) Intertrochanteric AO/OTA A3 and subtrochanteric fractures treated with intramedullary nail (IMN). h) Best practice 2014 to 2018 mean values.

A mean 83% of patients (71% to 91%) was treated within 48 hours (Figure 2a) and 83% of patients (65% to 96%) were treated by an experienced surgeon (Figure 2b). For undisplaced FNFs screw fixation was used in 86% of patients (51% to 99%; Figure 2c).

The majority of patients (mean 96% (79% to 99%)) with a displaced FNF received an arthroplasty (Figure 2d), and a mean 80% of these patients (0.3% to 100%) had a cemented stem. Seven of the 43 hospitals used a cemented prosthetic stem in fewer than 40% of the arthroplasties in contrast to five hospitals that used bone cement in all patients (100%; Figure 2e).

In trochanteric fractures the mean proportion receiving guideline-recommended treatment with a SHS was 68% (0% to 99%; Figure 2f). In inter- and subtrochanteric fractures, the mean proportion of patients treated with the recommended IMN was 76% (9% to 100%). In 14 hospitals (33%) the mean proportion receiving IMN for such fractures was below 30%, while 16 hospitals used IMN in more than 90% of patients (Figure 2g).

The mean composite best practice indicator for the group of hip fractures in January 2014 to December 2018 was 55% (Figure 2h).

During the five-year study period, adherence improved for all fracture types, except for trochanteric fractures (Figure 3); the mean composite "best practice indicator" increased from 50% (2014) to 59% (2018).

Fig. 3

Fracture specific adherence to best practice January 2014 to December 2018. Values given as mean percent adherence to fracture specific guideline recommendation.FNF, femoral neck fracture,OTA, Orthopaedic Trauma Association.

Predictors for adherence to guidelines

Adherence to guidelines, expressed by the composite measure of best practice calculated for all hip fractures, is shown in Table V. Hospitals with a dedicated hip fracture unit adhered more often to guidelines than those without such a unit (OR 1.06 (95% CI 1.01 to 1.11); p = 0.025). Furthermore, hospitals with a hip fracture programme were more compliant in following guidelines compared to hospitals without such a programme (OR 1.16 (95% CI 1.06 to 1.27); p = 0.002). The effect of hospital treatment volume on adherence to guideline recommendations expressed by the term "best practice" varied significantly; with high volume hospitals as reference, both intermediate-high and low volume hospitals adhered significantly better to best practice (OR 1.08 (95% CI 1.02 to 1.14); p = 0.010, and OR 1.19 (95% CI 1.08 to 1.31); p < 0.001 respectively), whereas intermediate low volume hospitals underperformed (OR 0.82 (95% CI 0.76 to 0.87); p < 0.001). Table V also shows a gradual improvement in adherence to guidelines over the period studied.

There were also significant differences between the four regional health authorities (RHAs). With the most populated region (South-Eastern Norway RHA) as reference, Western Norway RHA and Central Norway RHA adhered significantly better to best practice (OR 1.50 (95% CI 1.39 to 1.60); p < 0.001, and OR 1.09 (95% CI 1.03 to 1.16); p = 0.006 respectively), whereas Northern Norway RHA did not differ significantly.

Consequences of deviation from guidelines

Guideline-recommended treatment and subsequent outcomes are presented in Table VI. Delayed surgery exceeding the recommended 48 hours increased 365 day mortality (OR 1.13 (95% CI 1.05 to 1.22); p = 0.001). Years of experience of surgeons did not affect any of the three outcome measures. For undisplaced FNFs, non-adherence to the recommended screw fixation reduced the risk of reoperation substantially (OR 0.34 (95% CI 0.21 to 0.55); p < 0.001). Patients with displaced FNF receiving treatment alternatives other than the recommended arthroplasty had a statistically significantly higher 30 day mortality rate (OR 1.29 (95% CI 1.03 to 1.62); p = 0.030), a higher 365 day mortality rate (OR 1.45 (95% CI 1.22 to 1.72); p < 0.001) and a higher 365 day reoperation rate (OR 4.61 (95% CI 3.73 to 5.71); p < 0.001). Patients treated with arthroplasty without the recommended cemented stem had a statistically significant higher 365 day reoperation rate (OR 1.23 (95% CI 1.02 to 1.48); p = 0.030). Patients with trochanteric fractures not treated with the recommended SHS had a significantly lower 365 day mortality rate (OR 0.85 (95% CI 0.75 to 0.98); p = 0.023). For inter- and subtrochanteric fractures the risk of reoperation increased significantly if recommended treatment with IMN was not employed (OR 1.54 (95% CI 1.10 to 2.16); p = 0.012).