Fast Facts Fast Facts: Rheumatoid Arthritis John D Isaacs and Larry W Moreland Second edition
Fast Facts Fast Facts: Rheumatoid Arthritis Second edition John D Isaacs PhD FRCP Professor of Clinical Rheumatology and Director Wilson Horne Immunotherapy Centre Newcastle University Consultant Rheumatologist, Freeman Hospital Newcastle-upon-Tyne, UK Larry W Moreland MD Chief of Rheumatology Division of Rheumatology and Clinical Immunology University of Pittsburgh USA Declaration of Independence This book is as balanced and as practical as we can make it. Ideas for improvement are always welcome: feedback@fastfacts.com
Fast Facts: Rheumatoid Arthritis First published 2002 Second edition May 2011 Text 2011 John D Isaacs, Larry W Moreland 2011 in this edition Health Press Limited Health Press Limited, Elizabeth House, Queen Street, Abingdon, Oxford OX14 3LN, UK Tel: +44 (0)1235 523233 Fax: +44 (0)1235 523238 Book orders can be placed by telephone or via the website. For regional distributors or to order via the website, please go to: www.fastfacts.com For telephone orders, please call +44 (0)1752 202301 (UK, Europe and Asia Pacific), 1 800 247 6553 (USA, toll free) or +1 419 281 1802 (Americas). Fast Facts is a trademark of Health Press Limited. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the express permission of the publisher. The rights of John D Isaacs and Larry W Moreland to be identified as the authors of this work have been asserted in accordance with the Copyright, Designs & Patents Act 1988 Sections 77 and 78. The publisher and the authors have made every effort to ensure the accuracy of this book, but cannot accept responsibility for any errors or omissions. For all drugs, please consult the product labeling approved in your country for prescribing information. Registered names, trademarks, etc. used in this book, even when not marked as such, are not to be considered unprotected by law. A CIP record for this title is available from the British Library. ISBN 978-1-905832-91-0 Isaacs JD (John) Fast Facts: Rheumatoid Arthritis/ John D Isaacs, Larry W Moreland Medical illustrations by Dee McLean, London, UK. Typesetting and page layout by Zed, Oxford, UK. Printed in China with Xpedient Print Services.
Introduction 5 The normal joint 7 Etiology 13 Pathogenesis 23 Epidemiology 37 Clinical features 43 Investigation 59 Assessment 69 Management traditional measures 80 Management biological therapies 93 Therapeutic developments 105 Useful addresses 111 Index 113
Introduction Rheumatoid arthritis (RA) is the commonest inflammatory joint disease, affecting approximately 1% of adults in the developed world. Here, we provide an easy-to-read and up-to-date overview of how RA is thought to develop, how it is diagnosed and monitored, and how it is treated, incorporating the major advances in these areas that have taken place since the first edition. The pathogenesis of RA is starting to become unraveled and, more than in any other disease, this has led to powerful targeted treatments. Specifically, nine targeted biological therapies have, at the time of press, received approval by regulatory agencies. These target inflammatory mediators and the cells that coordinate the dysregulated immune and inflammatory responses that characterize RA. They are discussed in the closing chapters of the book, along with our thoughts on future directions of investigation and management. We also cover the new classification criteria for RA, and a new autoantibody class, anti-citrullinated peptide antibody (ACPA), is discussed in the context of its use for diagnosing RA. 5
1 The normal joint Synovium The synovial membrane lines the non-weight-bearing aspects of the synovial cavity and is divided into the lining layer or intima and sublining layer or subintima. It is the target tissue of the dysregulated inflammation and immunity that characterizes rheumatoid arthritis (RA) (Figure 1.1). The synovial membrane intima is just one or two cell layers thick and contains two major cell types: type A synoviocytes, which bear macrophage markers, and type B synoviocytes, which have fibroblastic characteristics. The intima lacks the typical features of an epithelium and does not possess a basement membrane or tight intercellular contacts between synoviocytes. The matrix of the intima is rich in proteoglycans and glycosaminoglycans, in particular hyaluronic acid. The subintima is a loose vascular connective tissue stroma containing blood vessels, lymphatics and nerve endings within a BONE Capsule Synovium Articular cartilage Joint space BONE Inflamed, hyperplastic synovium Pannus invading and destroying articular cartilage and subchondral bone Figure 1.1 Normal joint anatomy (left side of figure) and RA pathology (right). 7
Fast Facts: Rheumatoid Arthritis matrix comprising varying proportions of lipid, collagen fibrils and more organized fibrous tissue. Synovial fluid The synovial membrane secretes lubricating and nourishing synovial fluid, a viscous fluid containing a high concentration of hyaluronic acid. Other constituents include nutrients and solutes that diffuse from the blood vessels in the subintima. The precise physiology of synovial fluid production is unknown, but exchange of fluid between the circulation and the joint space is governed by a balance of hydrostatic, osmotic and convective forces. As well as providing an osmotic force within the synovial cavity, hyaluronic acid contributes to the lubricating properties of synovial fluid although other constituents are also important. 8 Articular cartilage Articular cartilage comprises chondrocytes embedded in a hydrated matrix composed of collagen, proteoglycans and other matrix proteins. It is an avascular structure lacking lymphatics, and the synovial fluid is critical for providing nutrients to this tissue. Water makes up approximately 70% of normal cartilage by weight, whereas chondrocytes occupy only 5 10% by volume. Because of their low density, chondrocytes do not come into contact with one another directly but possess cellular processes which abut the matrix. These cells are critical to the integrity of articular cartilage because they synthesize collagen, proteoglycans and also other components such as fibronectin. Each cell is surrounded by a zone of secreted proteoglycans and a basket-like mantle of fibrillar collagen, but the highest collagen content occurs in the more distal intercellular matrix. Collagens are fibrillar proteins that, together with proteoglycans, account for the biomechanical properties of articular cartilage. There are 14 different types of collagen, divided into three major groups. The predominant collagen in articular cartilage is type II, constituting approximately 90% in the adult, with types IX and XI contributing most of the remainder. All collagens are based on a triple helical structure (Figure 1.2), and the differences between collagens relate to
6 Investigation Initial investigations of inflammatory arthritis (Table 6.1) are guided, on the one hand, by the differential diagnosis (see Table 5.1) and, on the other, by predictors of damage or prognosis (see Chapter 7). TABLE 6.1 Investigation of recent-onset polyarthritis or polyarthralgia* Inflammatory markers C-reactive protein Plasma viscosity Erythrocyte sedimentation rate Hematology Full blood count with differential white cell count Lupus anticoagulant* Biochemistry Renal function, including urine analysis Hepatic function Calcium, phosphate Uric acid Thyroid function tests Serum angiotensin-converting enzyme* Vitamin D, parathyroid hormone* Creatine kinase Immunology ACPA Rheumatoid factor Anti-nuclear antibody Serum immunoglobulins, including electrophoresis Anti-neutrophil cytoplasmic antibody* Anti-cardiolipin antibody* Complement screen* Cryoglobulins* Tissue typing: HLA-DR, HLA-B27* Virology/microbiology* Parvovirus serology Antistreptolysin O titer Rubella serology Influenza serology Mycoplasma serology Hepatitis B and C serologies HIV serology CONTINUED 59
Fast Facts: Rheumatoid Arthritis TABLE 6.1 (CONTINUED) Yersinia serology Campylobacter serology Lyme disease serology in endemic areas Stool/urethral cultures Synovial fluid To exclude infection Positively or negatively birefringent crystals End-organ investigation Radiology of appropriate joints HRUS if available MRI* Chest X-ray* Pulmonary function tests* Electrocardiogram* Echocardiogram* Nerve conduction studies/ electromyography* Dual X-ray absorptiometry scan* *Dictated by the clinical picture. ACPA, anti-citrullinated peptide antibody; HLA, human leukocyte antigen; HRUS, high-resolution ultrasound. 60 Immunologic investigations Rheumatoid factor (RF) is an autoantibody with specificity for the Fc region of the immunoglobulin (Ig)G molecule (Figures 6.1 and 3.7). IgM RF is present in up to 75% of RA patients during the course of their disease, although it may be absent at presentation. In contrast, its presence may predate the onset of RA by several years (see page 18). Its precise role in the pathogenesis of RA is unclear, but it is associated with more aggressive disease and extra-articular manifestations. RF is not specific for RA, but may accompany other autoimmune diseases, various acute and chronic infections and certain malignancies (Table 6.2). The serum titer of RF does not generally correlate with disease activity, except in patients with vasculitis (see page 56), who tend to have a high titer. Conventional tests measure IgM RF, however, whereas some models of RA pathogenesis implicate IgG or IgA RF, which may also be better predictors of long-term prognosis (see