Preface

It is well known that the prevalence of chronic diseases is increasing rapidly worldwide, and approximately one-third of all adults globally suffer from more than one chronic condition. The prevalence rates of "multiple chronic conditions" (MCC), which indicates the presence of two or more chronic health conditions simultaneously in the same individual, are quite heterogeneous and show regional differences across the world. It is inevitable that MCC (also known as "multimorbidity") is becoming increasingly common as the world's population ages. As such, it is one of the greatest global health challenges associated with adverse individual, public, and financial outcomes, both now and in the future. *An Overview and Management of Multiple Chronic Conditions* is an up-to-date source of information for physicians, residents, and advanced medical students seeking a broader understanding of managing chronic disease clusters. The authors of the chapters come from many eminent centers around the world and are experts in their respective fields.

Considering MCC management in a broader context, the transition from a single disease-focused perspective to a patient-centered holistic approach may require considerable time and tremendous effort from health professionals and healthcare providers. Its burden to both the individual and society is increasing, probably due to lowered thresholds for diagnoses, advances in medical care, greater life expectancy, and possibly due to a true increase in the prevalence of some chronic diseases. Rheumatic and musculoskeletal diseases, which are among the most prevalent groups of non-communicable diseases, are highly variable medical conditions ranging from inflammatory rheumatic diseases and degenerative conditions to fragility conditions and regional pain syndromes. These diseases are the top three greatest contributors to years lived with disability in almost all world regions, as they are strong determinants of pain and disability limiting people's ability to manage their health. These diseases are also highly susceptible to MCC (especially in osteoporosis, osteoarthritis, and inflammatory arthritis) possibly due to their high incidence and low case fatality rate. They usually aggregate with a wide set of non-communicable diseases such as hypertension, cardiovascular diseases, dyslipidemia, diabetes, mental health problems, depression, and/or metabolic conditions. Recent studies also demonstrate that patients with chronic respiratory conditions, such as obstructive sleep apnea, chronic obstructive pulmonary disease, or idiopathic pulmonary fibrosis, commonly experience cognitive impairment as well. However, mild cognitive impairment is grossly underdiagnosed and undertreated by primary care physicians. Physicians who notice signs of memory loss, disorientation, gait impairment, or even poor adherence to pharmacologic/ nonpharmacologic treatment should screen their patients for cognitive dysfunction and refer them to a neurologist for a thorough evaluation. Physicians should also be aware of prevention strategies for cognitive dysfunction in chronic respiratory diseases. In addition, special caution should be taken with cognitive-related comorbidities with which these respiratory conditions are associated such as cerebrovascular diseases, cardiovascular pathology, and diabetes mellitus.

Hearing impairment, hearing loss, or deafness is also one of the leading causes of years lived with a disability. Untreated hearing loss negatively affects communication and social engagement, leading to reduced quality of life. In addition, it is a potentially modifiable risk factor for dementia. Presbycusis, also called age-related hearing loss, is one of the most frequent hearing disorders among elderly people. Similarly, presbycusis-related tinnitus and cognitive impairment are common disorders in older adults that are almost always unnoticed at the early stage. Identification of the complex and mutual interactions among hearing loss, tinnitus, and cognitive impairment in connection with decreased peripheral hearing perception and central nervous system dysfunction suggested that comprehensive assessment, intervention, and treatment in consideration of these three diseases are important to decay aging. On the other hand, some cases of sensorineural hearing loss associated with many immune-mediated inflammatory diseases with variable prevalence in the population have also been reported. Psoriasis, one of these inflammatory diseases, is a common, lifelong multisystemic chronic disease that has multiple clinical types in a spectrum ranging from mild erythemato-squamous skin lesions to psoriatic arthritis. Like other diseases in this group, psoriatic disease is often accompanied by certain comorbidities such as metabolic syndrome, diabetes mellitus, cardiovascular disease, obesity, and psychiatric disturbances. However, physicians, especially dermatologists and rheumatologists, need to be more aware of the prevalence and clinical relevance of subclinical sensorineural hearing loss (as a neglected but important comorbidity) in psoriasis and psoriatic arthritis.

As a result of different physical, psychological, and cognitive challenges, multiple unnecessary or inappropriate drug use for self-care and disease management in patients with MCC leads to an increased risk of polypharmacy, inadequate treatment, adverse drug events, and drug–drug interactions. Recent reviews of multiple sclerosis show that the physical and psychiatric comorbidities (mostly hypertension, hyperlipidemia, chronic lung disease, depression, anxiety) are common and associated with disability progression, lesion accrual on magnetic resonance imaging, diminished quality of life, hospitalizations, and even mortality. However, little is known about how comorbidities influence multiple sclerosis-related treatment. Currently, there is no definitive treatment for this demyelinating disorder with an underlying neuroinflammatory disease process. It is suggested that relapsing-remitting multiple sclerosis is accompanied by decreases in serum endogenous enkephalins/endorphins and alterations in inflammatory cytokines. Low doses of naltrexone (an opioid receptor antagonist) to upregulate the body's own production of enkephalins has been shown by a number of clinical trials to be a safe adjuvant or primary treatment for relapsing-remitting multiple sclerosis. This alternative biotherapeutic continues to be associated with stabilizing multiple sclerosis, leading to improvement in peripheral spasticity and mental health composite scores without inducing any side effects. In addition, it does not appear to interfere with other disease-modifying therapies. Although traditional/complementary/alternative medicine practices have been often applied by physician/non-physician practitioners in recent years, it is highlighted that scientific investigations regarding potential benefits should be supported, and proven benefits need to be brought into modern medicine. There is evidence that traditional Chinese medicine for geriatric syndromes (including "Jia wei weng dan tang" and "ba wei di huang wan" treatments for dementia, "Yi-gan San" treatment for behavioral and psychological symptoms of dementia, "Banxia Houpo Tang" treatment for aspiration pneumonia, and "Da Jian Zhong Tang" treatment for chronic constipation) are partly accepted by modern medical doctors.

**V**

Every clinician, whether a general practitioner or a specialist who frequently encounters complex patients, should become increasingly aware of the clinical relevance and undeniable burden of multiple physical, cognitive, and/or mental chronic condition clusters. It is obvious that there is a growing need for population-

**Dr. Sevgi Akarsu**

Faculty of Medicine, Dokuz Eylül University,

Department of Dermatology,

Professor,

Izmir, Turkey

based studies to determine the best management for MCC.

Every clinician, whether a general practitioner or a specialist who frequently encounters complex patients, should become increasingly aware of the clinical relevance and undeniable burden of multiple physical, cognitive, and/or mental chronic condition clusters. It is obvious that there is a growing need for populationbased studies to determine the best management for MCC.
