Several factors make it difficult and challenging to investigate rheumatological diseases:

• 1.
  

  The wide array of investigations currently available.

  
  
• 2.
  

  The variable access to investigations across the globe and their potential cost.

  
  
• 3.
  

  The validity and acceptability of investigations.

  
  
• 4.
  

  The gap in knowledge regarding the usefulness or otherwise of a particular investigation.

In this issue of the journal, expert authors from across the globe have discussed the complexities of the issues involved in making rheumatological diagnoses. The multisystem presentation of some rheumatological conditions can be highly perplexing, and a delay in diagnosis may prove detrimental to a satisfactory outcome. An approach to multisystem presentation is provided by Watts. Other authors have exhaustively reviewed the approach to the more specific situations of new-onset polyarthritis (see chapter by Ashok Kumar) and spinal pain (see chapter by Braun, Baraliakos, Regel and Kiltz). Sen, Clarke and Ramanan provide a very useful clinical guide for the assessment of a child with joint pains presenting to primary care physicians. They also provide guidance on the appropriate referral of children to paediatric rheumatologists, oncologists, orthopaedic surgeons and the emergency department.

Several infections can cause arthritis, and the investigative approach to this problem has improved substantially. Mathew and Ravindran have extensively reviewed the approach to each type of arthritis, emphasizing the diagnostic tests, along with their statistical accuracy. They have also discussed newer methods such as nucleic acid amplification using the polymerase chain reaction along with pitfalls in interpreting the tests. Travel to and from the developing world has led to an increase in travel-related musculoskeletal problems mainly due to infections. The Western clinician’s lack of familiarity with the types of infections may lead to a delay in early and correct diagnosis. Adizie and Adebajo have lucidly reviewed the impact of global migration on rheumatological clinical practice.

Chronic pain is a common problem seen in rheumatology clinics. It can be multifactorial; therefore, establishing a reliable diagnosis is the primary challenge in evaluating a patient with chronic pain. Hauge and Shenker have provided an excellent review of a practical approach to chronic pain.

Amita Aggarval has reviewed the role of autoantibody testing in the assessment of rheumatic diseases with great authority. In their chapter, Malaviya and Kapoor have discussed the cost-effectiveness of various investigations in the context of resource-poor developing countries. Both these chapters highlight the fact that there are no ‘routine’ tests in rheumatology, and all investigations should be conducted only when the context is correct and the clinical question is clear.

Whether the classification criteria can be used as diagnostic criteria or not remains a widely debated topic. June and Aggarval argue that, despite shortcomings, classification criteria can be still used for understanding the disease as well as a guide for diagnosis with a few caveats. They have discussed the limits of the current classification criteria and described their use and abuse in clinical practice, including how they should be used with caution when applied in clinics.

We sincerely hope that both trainees and practising clinicians alike will find this issue useful in their everyday practice.