foot and ankle characteristics associated with falls in adults with rheumatoid arthritis

236 Pages·2016·14.73 MB·English

Foot and ankle characteristics
associated with falls and falls risk in
adults with rheumatoid arthritis

Angela Robyn Brenton-Rule

A thesis submitted to Auckland University of Technology
in fulfilment of the requirements for the degree of Doctor
of Philosophy (PhD)
2015

School of Clinical Sciences

Primary Supervisor: Professor Keith Rome
FORM
DEPOSIT OF THESIS/EXEGESIS/DISSERTATION IN THE AUT LIBRARY
PGR15
 This form must be typed. Handwritten forms will not be accepted.
PLEASE NOTE
 The completed and signed form should be bound into the copy of the thesis/exegesis intended for the AUT University
Library
 If the work is to be treated as confidential or is embargoed for a specified time, form PGR16 must also be completed
and bound into the thesis/exegesis.

Student ID No 0317047 Name Angela Brenton-Rule
Faculty Health & Environmental Sciences School/Dept Podiatry
Year of submission
Programme PhD 2015
(for examination)
Research Output Thesis Exegesis Dissertation Points Value 360
Foot and ankle characteristics associated with falls and falls risk in adults with rheumatoid
Thesis Title
arthritis

DECLARATION

I hereby deposit a print and digital copy of my thesis/exegesis with the Auckland University of Technology Library. I
confirm that any changes required by the examiners have been carried out to the satisfaction of my primary
supervisor and that the content of the digital copy corresponds exactly to the content of the print copy in its entirety.
This thesis/exegesis is my own work and, to the best of my knowledge and belief, it contains:
 no material previously published or written by another person (except where explicitly defined in the
acknowledgements);
 no material which to a substantial extent has been submitted for the award of any other degree or diploma of a
university or other institution of higher learning.

CONDITIONS OF USE

From the date of deposit of this thesis/exegesis or the cessation of any approved access restrictions, the conditions
of use are as follows:
1. This thesis/exegesis may be consulted for the purposes of private study or research provided that:
(i) appropriate acknowledgement is made of its use;
(ii) my permission is obtained before any material contained in it is published.
2. The digital copy may be made available via the Internet by the AUT University Library in downloadable, read-only
format with unrestricted access, in the interests of open access to research information.
3. In accordance with Section 56 of the Copyright Act 1994, the AUT University Library may make a copy of this
thesis/exegesis for supply to the collection of another prescribed library on request from that library.

THIRD PARTY COPYRIGHT STATEMENT

I have either used no substantial portions of third party copyright material, including charts, diagrams, graphs,
photographs or maps, in my thesis/exegesis or I have obtained permission for such material to be made accessible
worldwide via the Internet. If permission has not been obtained, I have asked/will ask the Library to remove the third
party copyright material from the digital copy.
Student’s Signature Date 18/01/2016
i

ABSTRACT

The thesis investigated whether foot and ankle characteristics are associated with falls
or falls risk in adults with rheumatoid arthritis (RA). A systematic review of the
incidence and risk factors for falls in people with RA found inconsistency in methods
for collecting falls data and conflicting evidence about fall risk factors. The current
study sought to extend our understanding of fall risk in people with RA through the
inclusion of foot and ankle characteristics.

The thesis consisted of a cross-sectional study followed by a 12-month prospective
study of 201 adults with established RA. In the cross-sectional study, falls experienced
in the preceding year were recorded (12-month fall history) and a range of clinical and
foot and ankle characteristics were measured. Participants were then followed for 12
months to record the occurrence of prospective falls following the Prevention of Falls
Network Europe (ProFaNE) consensus guidelines for falls research. Data analysis
involved both univariate and multivariate analysis.

Falls incidence for the cross-sectional study was 59%. The logistic regression analysis,
controlling for age, identified (a) clinical and foot and ankle characteristics which were
independently associated with falls in the preceding 12 months; and (b) clinical and
foot and ankle characteristics that were independent predictors of prospective falls.
Clinical and foot and ankle characteristics that were independently associated with
falls in the preceding 12 months included cardiovascular disease (odds ratio (OR) 3.22,
P=0.024), midfoot peak plantar pressure (OR 1.12 [for each 20 kPa increase], P=0.046)
and foot-related disability and impairment (OR 1.17 [for each 3 point increase],
P=0.005).

Falls incidence for the 12-month prospective study was 42%. Clinical and foot and
ankle characteristics found to be independent predictors of prospective falls (not
controlling for 12-month fall history) included psychotropic medication (OR 2.35,
P=0.025) and presence of foot or ankle tender joints (OR 1.95, P=0.034). When 12-
month fall history was included in the analysis, psychotropic medication (OR 2.34,
ii

P=0.025) and 12-month fall history (OR 2.27, P=0.008) were independent predictors of
falls.

Falls are complex, multi-system events with multifactorial aetiologies. Therefore, no
single risk factor can be identified as the cause of any given fall event. As such, the
thesis presented a synthesis of the findings relating to the foot and ankle fall risk
factors, with a hypothetical model on how these risk factors might be interrelated.
Further work is required to test the hypotheses relating to interrelationships between
foot and ankle fall risk factors.

Clinical implications included a number of assessments that could be incorporated into
routine clinical practice to identify or monitor fall risk in people with established RA.
Future work is needed to confirm the study findings in people with early RA and to
develop a tool to screen for falls risk, and predict falls, in people with RA. Future
research could include dynamic tests of balance, 3D gait analysis of lower limb and
foot function and assessment of lower leg muscle strength and ankle joint
proprioception. In addition, further evaluation of the role of footwear in falls, in people
with RA, is warranted. Qualitative research, exploring perceptions around falls and falls
risk, and the development of expert consensus guidelines for participant grouping in
falls data analysis, would benefit future RA falls research.
iii

TABLE OF CONTENTS
ABSTRACT ........................................................................................................................... i
LIST OF FIGURES ............................................................................................................. viii
LIST OF TABLES ................................................................................................................. ix
AUTHORSHIP .................................................................................................................... xi
ACKNOWLEDGEMENTS ................................................................................................... xii
DISSEMINATION ............................................................................................................. xiii
GLOSSARY OF ABBREVIATIONS ....................................................................................... xv
TERMINOLOGY ...............................................................................................................xvii
CHAPTER 1: INTRODUCTION ............................................................................................. 1
1.1: Overview ................................................................................................................ 1
1.2: Thesis structure ..................................................................................................... 2
CHAPTER 2: RHEUMATOID ARTHRITIS AND THE FOOT .................................................... 4
2.1: Introduction ........................................................................................................... 4
2.2: Search strategy ...................................................................................................... 4
2.3: Background to rheumatoid arthritis ..................................................................... 4
2.4: Predisposing factors for RA ................................................................................... 6
2.5: Diagnosis of RA ...................................................................................................... 7
2.6: Measuring disease activity .................................................................................... 8
2.7: Measuring functional ability and activity limitation ............................................ 9
2.8: Treatment of RA .................................................................................................. 10
2.9: Classification criteria for RA ................................................................................ 12
2.10: Foot involvement in RA ..................................................................................... 13
2.10.1: Epidemiology ............................................................................................... 13
2.10.2: Foot pain ...................................................................................................... 13
2.10.3: Detection of foot pathology ........................................................................ 14
2.10.4: Progression of foot pathology ..................................................................... 14
2.10.5: Foot-related impairment ............................................................................. 16
2.10.6: Patient-reported foot-related disability and impairment ........................... 20
2.11: Summary ............................................................................................................ 20
CHAPTER 3: FALLS IN ADULTS WITH RHEUMATOID ARTHRITIS ...................................... 21
3.1: Introduction ......................................................................................................... 21
3.2: Search strategy .................................................................................................... 21
iv

3.3: Studies identified in the search........................................................................... 21
3.4: Falls incidence ...................................................................................................... 24
3.5: Fall risk factors ..................................................................................................... 24
3.5.1: Physiological risk factors ................................................................................ 24
3.5.2: Pharmacological risk factors .......................................................................... 26
3.5.3: Extrinsic risk factors ....................................................................................... 26
3.5.4: Measures of RA disease activity .................................................................... 27
3.6: Methodological considerations in RA falls research .......................................... 27
3.6.1: Recording of falls data ................................................................................... 27
3.6.2: Measurement of fall risk factors ................................................................... 28
3.7: Future directions .................................................................................................. 29
3.8: Summary .............................................................................................................. 31
3.9: Additional studies ................................................................................................ 31
CHAPTER 4: AIMS OF THE THESIS ................................................................................... 32
4.1: Introduction ......................................................................................................... 32
4.2: Research questions .............................................................................................. 32
4.3: Null hypotheses ................................................................................................... 33
CHAPTER 5: IDENTIFICATION OF FOOT AND ANKLE MEASURES .................................... 34
5.1: Introduction ......................................................................................................... 34
5.2: Search strategy .................................................................................................... 34
5.3: Foot and ankle characteristics associated with falls, impaired balance and
functional ability in older adults ................................................................................ 34
5.4: Foot and ankle measures identified for inclusion in the observational study .. 36
CHAPTER 6: METHODOLOGY .......................................................................................... 39
6.1: Introduction ......................................................................................................... 39
6.2: Ethical approval ................................................................................................... 39
6.3: Recruitment and sampling .................................................................................. 39
6.4: Participant inclusion and exclusion criteria ........................................................ 40
6.5: Research environment ........................................................................................ 40
6.6: The researcher ..................................................................................................... 40
6.7: Demographics and clinical characteristics .......................................................... 41
6.8: RA disease activity ............................................................................................... 41
6.9: Fear of falling ....................................................................................................... 42
v

6.10: Foot pain, impairment and disability ................................................................ 42
6.11: Footwear ............................................................................................................ 43
6.12: Procedures ......................................................................................................... 43
6.12.1: Foot-type ..................................................................................................... 43
6.12.2: Foot deformity ............................................................................................. 45
6.12.3: Neuropathy .................................................................................................. 45
6.12.4: Muscle strength ........................................................................................... 47
6.12.5: Ankle range of motion ................................................................................. 48
6.12.6: Gait and balance .......................................................................................... 49
6.13: Falls outcome ..................................................................................................... 50
6.14: Statistical analysis .............................................................................................. 53
6.14.1: Explanation of terms .................................................................................... 53
6.14.2: Grouping of participants for univariate analysis ......................................... 53
6.14.3: Grouping of variables for data analysis ....................................................... 54
6.14.4: Cross-sectional analysis ............................................................................... 55
6.14.5: Prospective analysis ..................................................................................... 56
6.14.6: Subsequent analysis .................................................................................... 57
CHAPTER 7: CROSS-SECTIONAL STUDY RESULTS ............................................................ 59
7.1: Introduction ......................................................................................................... 59
7.2: Recruitment ......................................................................................................... 59
7.3: Participant characteristics ................................................................................... 61
7.4: Primary univariate analysis comparing non-fallers and fallers ......................... 65
7.5: Primary multivariate analysis of predictive risk factors comparing non-fallers
and fallers .................................................................................................................... 67
7.6: Secondary univariate analysis ............................................................................. 69
7.6.1: Comparing non-fallers, single-fallers and multiple-fallers ............................ 69
7.6.2: Comparing the combination of non-fallers/single-fallers with multiple-fallers
................................................................................................................................. 71
7.7: Secondary multivariate analysis of predictive risk factors comparing the
combination of non-fallers/single-fallers with multiple-fallers ............................... 73
7.8: Correlations between foot and ankle variables and PROMs ............................. 75
7.9: Summary of the cross-sectional findings ............................................................ 77
7.9.1: Findings for clinical characteristics ................................................................ 77
7.9.2: Findings for research question 1 ................................................................... 77
vi

7.9.3: Findings for research question 2 ................................................................... 78
CHAPTER 8: CROSS-SECTIONAL STUDY DISCUSSION ...................................................... 79
8.1: Introduction ......................................................................................................... 79
8.2: Discussion............................................................................................................. 79
8.2.1: Clinical characteristics ................................................................................... 80
8.2.2: Foot and ankle characteristics ....................................................................... 83
8.3: Summary .............................................................................................................. 88
CHAPTER 9: PROSPECTIVE STUDY RESULTS .................................................................... 90
9.1: Introduction ......................................................................................................... 90
9.2: Participant 12-month retention in the study for falls data and second study
visit .............................................................................................................................. 90
9.3: Falls incidence ...................................................................................................... 91
9.4: Primary univariate analysis comparing non-fallers and fallers ......................... 92
9.5: Primary multivariate analysis of predictive risk factors comparing non-fallers
and fallers .................................................................................................................... 94
9.6: Secondary univariate analysis ............................................................................. 96
9.6.1: Comparing non-fallers, single-fallers and multiple-fallers ............................ 96
9.6.2: Comparing the combination of non-fallers/single-fallers with multiple-fallers
................................................................................................................................. 98
9.7: Secondary multivariate analysis of predictive risk factors comparing the
combination of non-fallers/single-fallers with multiple-fallers ............................... 99
9.8: Negative binomial regression modelling .......................................................... 100
9.9: Subsequent analysis .......................................................................................... 101
9.9.1: Analysis of foot and ankle characteristics measured at 12-months ........... 101
9.9.2: Comparing foot and ankle characteristics at baseline and 12-months ....... 101
9.10: Summary of prospective findings ................................................................... 102
9.10.1: Findings for clinical characteristics ............................................................ 102
9.10.2: Findings for research question 3 ............................................................... 102
CHAPTER 10: PROSPECTIVE STUDY DISCUSSION .......................................................... 103
10.1: Introduction ..................................................................................................... 103
10.2: Discussion ........................................................................................................ 103
10.2.1: Clinical characteristics ............................................................................... 104
10.2.2: Foot and ankle characteristics ................................................................... 107
10.3: Summary .......................................................................................................... 109
vii

CHAPTER 11: THESIS OVERVIEW AND CLINICAL IMPLICATIONS ................................... 110
11.1: Introduction ..................................................................................................... 110
11.2: Aims of the thesis ............................................................................................ 110
11.3: Overview of thesis findings ............................................................................. 111
11.4: Synthesis of thesis findings ............................................................................. 113
11.5: Study limitations .............................................................................................. 116
11.6: Study strengths ................................................................................................ 117
11.7: Clinical implications ......................................................................................... 120
11.8: Future directions.............................................................................................. 122
11.8.1: Clinician education .................................................................................... 122
11.8.2: Review of clinical guidelines ...................................................................... 123
11.8.3: Falls education ........................................................................................... 125
11.8.4: Further research ........................................................................................ 125
CHAPTER 12: OVERALL CONCLUSION ........................................................................... 130
REFERENCES .................................................................................................................. 133
APPENDICES .................................................................................................................. 151
Appendix 1: Ethics and locality approvals ............................................................... 151
Appendix 2: Participant consent form ..................................................................... 158
Appendix 3: Recruitment letters .............................................................................. 161
Appendix 4: Participant information sheet ............................................................. 165
Appendix 5: Recruitment poster .............................................................................. 169
Appendix 6: Clinical research form .......................................................................... 171
Appendix 7: Footwear chart ..................................................................................... 192
Appendix 8: Post-fall questionnaire ......................................................................... 194
Appendix 9: Subsequent prospective analysis ........................................................ 197
Appendix 10: Comparison of foot and ankle characteristics at baseline and 12-
months ...................................................................................................................... 198
Appendix 11: Systematic review .............................................................................. 199
Appendix 12: TekScan MatScan® reliability study .................................................. 210
viii

LIST OF FIGURES

Figure 2.1: ACR/EULAR 2010 Rheumatoid arthritis classification criteria ...................... 12
Figure 6.1: Calculation of the arch index (AI) ................................................................. 44
Figure 6.2: TekScan MatScan® ........................................................................................ 44
Figure 6.3: 10g Monofilament ........................................................................................ 45
Figure 6.4: Biothesiometer ............................................................................................. 46
Figure 6.5: Hand-held dynamometer ............................................................................. 47
Figure 6.6: Modified lunge test ....................................................................................... 48
Figure 6.7: Falls Calendar, sample calendar page........................................................... 52
Figure 7.1: CONSORT flow diagram for baseline participant recruitment and reasons
for non-attendance ........................................................................................................ 60
Figure 9.1: Flow diagram showing how person-years were calculated ......................... 91
Figure 11.1: Synthesis of findings for cross-sectional and prospective studies. .......... 114