Brazilian oral herbal medication for osteoarthritis: a systematic review protocol

Osteoarthritis is the most common musculoskeletal disease and is associated with significant functional decline and reduced quality of life [1]. It is characterized by loss of articular cartilage, subchondral bone remodeling, bone spurs, ligament laxity, weakening of the periarticular muscles, and thickening of the capsule and synovial membrane [2–4]. Osteoarthritis is the result of both mechanical and biological events that cause imbalance in the normal process of degradation and synthesis of joint cartilage chondrocyte, extracellular matrix, and subchondral bone [5].

The World Health Organization (WHO) states that osteoarthritis is a disease related to an aging population [6] and the leading cause of chronic disability in middle-aged and older populations [7]. The risk of osteoarthritis increases from 1 % in 30 years old people to almost 10 % in people over the age of 40 years and 50 % in people over the age of 60 years [8]. Osteoarthritis produces a variety of serious social problems, both health and economic and is one of the more debilitating musculoskeletal diseases among the elderly [9].

Osteoarthritis can be associated with pain, stiffness, and functional limitations [10–12]. It is estimated to affect 10 % of men and 18 % of women and occurs most often in the hip and knee [13].

Although treatment guidelines recommend analgesics as first-line drugs, the non-steroidal anti-inflammatory drugs are preferred, although they are less safe and more expensive [14]. Due to the high incidence of adverse events related to non-steroidal anti-inflammatory drugs (NSAID) and the high costs associated with adverse events (e.g., gastrointestinal bleeding or perforation, additional medical visits, diagnostic procedures, treatments, and hospitalizations), therapeutic alternatives are an area of great interest [15, 16].

The use of herbal medicines worldwide is substantial and increasing. In 2001, the USA, around 38 % of adults and 12 % of children report use of herbal medicine [17]. Use of herbal medicines in developing countries is even greater, and an estimated 85 % of the Brazilian population use plants or preparations of these for their healthcare [18]. In 2011, the Brazilian herbal market generated 1.1 billion in revenue, which included sales of 43 million units of phytomedicines [19].

In primary health care, the use of medicinal plants has been stimulated by guidelines from various national health conferences and by the WHO [20]. The National Policy of Integrative and Complementary Practices and the National Policy of Medicinal and Phytotherapeutic Plants adopted in 2006 were created to meet the demands of the Brazilian population. These policies were decisive steps towards introducing the use of medicinal and phytotherapeutic plants in the Brazilian Unified Health System (SUS) [21].

In Brazil, there are 13 herbal medications marketed for the treatment of osteoarthritis: Harpagophytum procumbens DC. ex Meisn., Uncaria tomentosa (Willd.) DC., Salix alba L., (financed by the government), Boswellia serrata Roxb. ex Colebr., Bowdichia virgilioides Kunth., Curcuma longa L. (or Curcuma domestica Valeton), Chenopodium ambrosioides L., Cordia curassavica (Jacq.) Roem. Schult. (or Cordia verbenacea DC.), Salix daphnoides Vill, Salix purpurea L., Persea gratissima Gaertn.f. (or Persea americana Mill.), Uncaria guianesis (Aubl.) J.F. Gmel, and Zingiber officinale Roscoe.

Two systematic reviews evaluated the use of herbal medicines for the treatment of osteoarthritis by topical and oral use, respectively [22, 23]. However, these studies did not include some of the plants marketed in Brazil: B. virgilioides Kunth, C. ambrosioides L, C. curassavica (Jacq.) Roem. Schult, S. alba L., and U. tomentosa (Willd.) DC. Of these plants, U. tomentosa (Willd.) DC. and S. alba L. are funded by the Brazilian government to use in the Unified Health System (SUS), and C. ambrosioides L. and C. curassavica (Jacq.) Roem. Schult are part of a list of plants of interest for development of research in order to include them as medicines financed by SUS.

Despite the common use of herbal medicines for managing osteoarthritis in adults, the safety and efficacy of some of these agents are uncertain. We therefore will conduct a systematic review of randomized controlled trials, which made use of oral herbal medicines used in Brazil for the treatment of osteoarthritis.