Introduction
Osteoporosis (OP) is a growing public health concern and affects more than 200 million people worldwide [
1]. Individuals living with OP are at greater risk of experiencing a fragility fracture. In developed countries, lifetime risk for a wrist, hip or vertebral fracture has been estimated at 30–40 % [
2]. For individuals aged 50 years and over, approximately one in two women and up to one in four men will experience an osteoporotic fracture [
3]. Worldwide, the disease has been reported to account for more than 8.9 million fractures annually [
4]. Due to the importance of fracture in the progression of OP, clinical trials investigating novel therapeutic agents have focused on endpoints relating to bone health and fracture incidence. The US Food and Drug Administration (FDA) approval requirements for new therapies emphasise reducing the risk of vertebral fracture along with maximising drug safety [
5].
While fracture incidence is clearly of clinical importance in OP, the extent to which it sufficiently captures outcomes that are patient-centred remains unclear, particularly given the potential impact of fracture on patients’ everyday lives such as mobility and other types of physical activity. Initially OP is considered asymptomatic, but this situation can change dramatically once a fracture has occurred. Fractures can result in reduced mobility and physical function. They can also result in chronic pain or affect the ability to self-care. Fractures can also have long-term consequences on physical function and greatly affect patients’ health-related quality of life (HRQL) [
6‐
9].
The importance of patient-centred outcomes when assessing new treatments is being recognised across a range of therapeutic areas. The FDA, along with the Patient-Centered Outcomes Research Institute (PCORI), has published guidance on the use of patient-reported outcomes (PROs) in product labelling and clinical research, respectively, and highlighted their value [
10,
11]. A greater awareness of patient-centred outcomes has the potential to guide treatment decisions and encourage more patient-focused prescribing. Nevertheless, PROs are assessed infrequently in OP clinical trials and when included, rarely involve more than a small subset of subjects. As a result, any opportunity to detect a meaningful change in PROs related to treatment is limited. Furthermore, in instances where benefits in PROs have been detected during well-controlled trials [
12‐
15], these outcomes have been omitted from product labels. As such, there is an increasing need to understand and capture patient-centred outcomes in OP. The objective of this paper is to use evidence and patient perspectives to provide insight on the effect of OP on patients’ physical function.
Methods
A multi-method approach was used to consolidate our understanding of physical function in OP. A systematic search and narrative literature review was conducted, to seek and summarise published evidence related to daily activities requiring physical function in OP. In addition, a secondary qualitative analysis of patient data, originally collected for the development of a PRO instrument, was performed. Finally, input was sought from key clinical thought leaders specialising in OP, to review, interpret and add to the findings of the literature review and interview analysis. The final result is a comprehensive perspective on the impact of OP and osteoporotic fragility fractures on physical function or performance.
Literature review
The literature search was designed to identify publications describing the impact of OP on daily activities and physical function. The search was conducted in MEDLINE and Embase using the web-based platform Ovid. Developing the search strategy was an iterative process with the initial use of draft searches, checking the outcome by reviewing a proportion of resulting abstracts for relevance and updating the search terms to improve the relevance of results. The initial search strategy included terms focused on OP and daily activities and function and was limited to more recent publications (published within 8 years) and those including patients aged ≥45 years. A further search strategy was developed to specifically identify qualitative studies that discussed the impact of OP on physical function and daily living from a patient’s perspective and was conducted in PsycINFO, in addition to MEDLINE and Embase. The final search terms are presented as a
supplementary appendix. Abstracts were reviewed and those deemed relevant were selected for full review. Articles were deemed relevant if they reported on the impact of OP on physical function/daily activities or the relationship between physical function and fracture occurrence.
Secondary qualitative analysis of interview transcripts
Given the lack of existing literature around OP and physical function from the patient perspective, a secondary thematic analysis of data collected during interviews with people with OP was performed. These interviews were originally conducted during the development of the Osteoporosis Assessment Questionnaire-Physical Function (OPAQ-PF) questionnaire, a PRO instrument developed to evaluate osteoporosis treatment effectiveness [
16]. During the instrument development process, 39 people with OP were recruited from three clinical centres in the USA, and concept elicitation and cognitive debriefing interviews were conducted. All patients were consented to the study, all interviews were conducted using a semistructured interview guide in a face-to-face setting by an experienced, trained interviewer and all were audio-recorded and transcribed. The sample was all female with a mean age of 70 years (standard deviation [SD] = 10.35), and the majority were white (
n = 34). All participants had been living with OP for at least 1 year, and the mean disease duration was 7.2 years (SD = 2.16). The majority of participants (
n = 27) had experienced one or more osteoporotic fractures, with most having had a single fracture (
n = 22). The maximum number of fractures experienced by a single participant was three. Fractures had occurred between 3 and 140 months (11.6 years) prior to being interviewed, with a mean time since fracture of 31.6 months (SD = 37.9). Participants with comorbidities were not excluded from the sample in order to reflect the wider OP population, as comorbid conditions are very common in this population. However, this made it more difficult in some cases to attribute impact on physical function to OP. Comorbidities included osteoarthritis, rheumatoid arthritis, diabetes, asthma and chronic obstructive pulmonary disease (COPD).
The secondary, thematic analysis of the interview data was conducted in two phases; the first was at a broad level to isolate relevant sections of the transcripts (i.e., those that focus on physical impacts of OP including any discussion of physical functioning, physical activities of daily living and the importance to patients of this type of impact). Data analyses were conducted by two of the authors (SS and CP) using MAXQDA 10, a qualitative analysis software tool that facilitates systematic coding. The two researchers (SS and CP) familiarised themselves with the data and generated initial codes on the same two transcripts. The initial codes were then compared, to check for consistency, ensuring that both researchers were including the same/very similar sections for further coding. The following stage of analysis involved coding the relevant sections in greater detail that related to OP impact on daily activities and physical function, the relative experience and impact of patients with osteoporotic fracture versus those who had not had osteoporotic fracture, and the importance of these impacts to patients. The codes identified during analysis were then grouped into themes which were then reviewed and defined by the researchers (SS and CP).
Review by clinical experts
Results from the literature review and secondary qualitative analysis of interview transcripts were reviewed and discussed with three clinical experts (LG, SR and DTG) specialising in OP with extensive experience in investigating HRQL, medication compliance and persistence, physical activity, exercise recommendations and OP interventions, through academic research, clinical practice or patient advocacy. Discussion took place during two in-depth telephone conferences, held on the 8th and 23rd May 2014. Specific questions considered in these discussions are presented in Table
1. Further input was sought through an iterative and collaborative process of developing a written summary of the discussions.
Table 1
Specific questions considered during discussions with OP experts
• What effect does decline in physical function have on the daily lives of people with OP? |
• What is the value of improvement of physical function and ability to perform daily activities requiring physical function to people with OP? |
• What is the value of maintaining physical function and the ability to perform daily activities requiring physical function to people with OP? |
• How strong is the relationship between fracture occurrence and ability to perform daily activities requiring physical function in OP? To what extent does this vary between individuals? |
• How much of the decline in physical function experienced by people with OP is not explained by fracture occurrence? |
• What other factors affect physical function and performance of daily activities requiring physical function in people with OP? |
• What are the unmet needs or gaps in current treatment in relation to the effect of OP on peoples’ performance of daily activities requiring physical function? |
• What is the added value of evaluating physical function to inform treatment effectiveness? What does measurement of physical function capture that is not already explained by fracture occurrence? |
The information gathered in the literature review, secondary qualitative analysis of patient interview transcripts and clinical input were consolidated and grouped by common themes. Quotes from patient interview transcripts are included to illustrate points from the perspective of people living with OP. Each quote is followed by details of the individual to link to the original data source (identification number) and provide contextual information to aid interpretation (their age, the number and location of fractures they have experienced, the length of time since fracture(s) in months and any comorbid conditions). Where relevant, the interviewer’s questions are stated in italics.
Discussion
While capturing fracture incidence is well-recognised as important in the study and management of OP, there is an increasing need to understand the physical impact of OP beyond fracture to ensure patient-centred research and management. The cycle of impairment presented here summarises how numerous factors can contribute to an increasing limited physical function in people with OP. Firstly, limiting activity can contribute to loss of muscle and bone strength and subsequently an increase in fracture risk. In turn, fracture occurrence can result in pain, fear of falling or changes in alignment, which can limit the performance of daily activities requiring physical function. Thus, a decrease in physical function can lead to an accumulation of impairment and activity restrictions over time.
Factors affecting outcomes across the physical, social and psychological spectrums are interrelated, and further elucidating these interactions is important to understand the true consequences of OP. The confounding effects of comorbidities and poor treatment compliance and persistence also must not be overlooked. This multifactorial picture of OP has important implications for treatment, as only once we understand all the factors that may influence an individual’s disease can we truly provide efficacious treatment. Limitations in physical function and restricted participation in society can occur gradually and are influenced by a range of factors including pain, availability of social support and the number of fractures. The situation can be made worse where vertebral fractures are not diagnosed or where advice from healthcare professionals is not based on validated assessment or sufficiently tailored to the individual.
The results of this review support that patient-centred outcomes are important to capture for evaluating treatment and managing the condition, as they provide additional insight into the impact of OP and fracture on the patient’s everyday life and overall well-being, improvement in which are key goals of treatment. Currently, few studies have examined the effect of pharmacologic treatment on physical function outcomes in OP, yet understanding the benefit of treatment in terms of physical function and everyday life activity would be valuable to inform physicians and help people with OP understand these potential benefits when making treatment decisions. This could, in turn, help to improve compliance and persistence with treatment. In contrast, studies of exercise often collect patient-centred outcomes [
61]. However, it might be advisable to agree on a core set of outcomes for future trials to facilitate comparisons.
The findings of this review also provide insight on how communication between healthcare professionals and people with OP could be improved in terms of the information and advice provided to patients related to physical function and activity. Information and advice provided to people with OP are an important factor in how they will respond and persist with treatment. In order to improve these interactions, our suggestion to clinicians and other healthcare professionals is to provide clear, simple explanations about the physiology, symptoms and potential impacts of OP on physical function at diagnosis, as well as the possibility of social and psychological issues that may also affect physical function. Having this greater awareness of the long-term consequences of OP in terms of physical function, body shape and everyday activity may encourage persons with OP to better comply and persist with treatment, as these impacts may be more salient to patients than fracture. In addition, in order to minimise the confusion around exercise recommendations, physicians should provide evidence-based exercise guidelines rather than generic advice to exercise, to walk or get more active, and should make referrals to exercise advice from physical therapists or exercise physiologists specialising in the treatment of OP.
The findings suggest that further investigation and research into certain areas related to OP and physical function would be useful. One such area is further assessing the relationship between muscle and bone strength in OP and how they interact when it comes to limitations in physical function and performance. It may also be valuable to investigate further the relationship among reduced societal participation, physical function and psychological impact. In particular, this would enable us to understand the possible effects of a reduction in societal participation that can occur as a result of OP. We would also suggest studies to evaluate the optimal way to engage people with OP in an appropriate and effective exercise treatment plan.
Limitations of this report should be acknowledged. With regards to the literature review, a key limitation was the insufficient classification of sample characteristics and methods in the selected publications. Most importantly, many publications failed to state whether the study participants had a confirmed diagnosis of OP, and others included mixed samples of those with OP and/or those who had experienced fractures. While some studies did make comparisons between OP patients with and without fractures, results were reported in terms of greater impact among fracture subgroups, rather than presenting results to describe the level of physical function and life impact among OP patients with or without fracture. The secondary qualitative analysis of interview transcripts was limited by the original aim to develop a specific PRO instrument. As a result, although problems relating to physical function and other factors influencing OP-related impairment were captured during the interviews, they were rarely explored in detail. Participants were not asked further questions regarding why a specific activity was problematic or how they felt about any limitations caused by their OP. Furthermore, in cases where participants did not report limitations, it is unclear whether they did not experience them or simply had not mentioned them during the interviews. In addition, many of the participants had comorbidities that also could impact physical function making it sometimes difficult to attribute an impact on physical function or activity to OP versus a comorbid condition. To address this limitation, input was sought from clinical experts through a review process to confirm validity and inform interpretation of the information reported.
In summary, OP and fracture can have a profound impact on physical function and everyday activity, and this impact accumulates over time through a cycle of impairment, as fracture leads to longer term detriments in physical function, including loss of muscle, activity avoidance and reduced physical capacity, which in turn leads to greater risk of fracture and potentially further reductions in physical function. This cycle of impairment is complex, as other physical, psychosocial and treatment-related factors, such as comorbid conditions, fears and beliefs about physical activity and risk of fracture influence limitations in physical activity and everyday function. More information on how treatments impact patients in terms of physical function and everyday activity would benefit both healthcare professionals and persons with OP in making treatment decisions and improving overall outcomes. Furthermore, informing patients about the potential long-term physical consequences of OP and impact on everyday life activity may help improve compliance and persistence with treatment, as these impacts may be more salient to patients than fracture incidence.