Keywords

These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

FormalPara Before You Start: Facts You Need to Know

  • Pain is common in patients with chronic kidney disease (50–70 % patients depending on study) and is often not recognized.

  • Pain is related to comorbidities and causes and complications of chronic kidney disease.

  • Pain can be controlled safely in patients with kidney disease, including those on dialysis.

  • Pain medication should be prescribed in a logical manner using a pain-control ladder.

  • Pain adversely affects quality of life so must not be ignored.

1 Pain in CKD

Pain is common – we have all experienced it. Unlike most things treated in medicine, the experience of pain is entirely subjective. We can recognize situations where we expect pain, such as fractures, tissue damage due to surgery, ischaemia, etc., but the pain itself is perceived differently by each individual. Pain can therefore only be diagnosed if we ask patients whether they have pain and how this is affecting them. How pain is experienced depends on many factors including culture, social support, mood as well as the pathology causing the pain. Often patients will not complain about chronic pain as they feel that this is part of their illness, that the healthcare team is not interested, or that any medication they have tried has been ineffective or has had side effects. Ideally, this should not happen as pain is known to be associated with depression and adversely affects quality of life.

1.1 Causes of Pain

It is not surprising that patients with CKD have such a high pain burden. As shown in Table 22.1, pain can be due to the underlying kidney disease, complications of poor kidney function, dialysis itself and comorbidities [1–3]. Determining the cause of pain therefore requires careful history taking. Indeed, patients may have often more than one cause of pain [1–3].

Table 22.1 Causes of pain related to CKD
Full size table

Increasingly, CKD is a disease of the elderly. Over 30 % of people over 80 years old have impaired kidney function. The majority of patients attending a general CKD clinic are therefore elderly and will have the general features and complications of ageing. Many of these are associated with pain as shown in Table 22.2.

Table 22.2 Causes of pain related to ageing
Full size table

1.2 Types of Pain

It is important to differentiate between acute and chronic pain. Acute pain is often associated with tissue damage, e.g. after injury or surgery. Dialysis patients may also experience episodes of acute pain during dialysis, such as headaches and cramps. Acute pain can be episodic but with periods without pain. In contrast, chronic pain is present for long periods of time and is often out of proportion with the extent of the originating injury. Experience of chronic pain by the patient will be affected by psychosocial factors as well as the underlying pathology causing the pain.

For the purpose of management, it is helpful to categorize pain into:

  • Nociceptive – pain due to tissue damage

  • Neuropathic – pain due to nerve damage

  • Mixed nociceptive and neuropathic – e.g. pain of peripheral ischaemia

  • Incident or movement related – caused by bone or joint damage; pain often absent at rest but more severe on movement

  • Other specific causes – such as renal colic, bowel obstruction

2 Screening and Assessment of Pain (Box 22.1)

Box 22.1. Screening and Assessment of Pain in CKD

Key Facts

  • Pain is perceived only by the patient, so can only be described by the patient.

  • Perception of pain is affected by mood and the meaning of pain for the patient.

Pain is not assessed routinely by renal clinicians and is therefore frequently not recognized. Routine and proactive assessment of pain is important [2, 3]. There are three global symptom assessment tools in regular use, which have been adapted and validated specifically for use in those with CKD. These are the renal version of the Palliative Outcome Scale – symptom module (POSs renal), the renal modified Edmonton Symptom Assessment Scale (ESAS) and the Dialysis Symptom Index (DSI). All three tools ask the patient about the presence and severity of common physical and psychosocial symptoms in CKD [4–7].

Understanding the nature, severity and need for treatment of pain is a challenge and takes time. Many patients do not discuss their pain if they feel that the healthcare team is not interested, is rushed, or that treatment is ineffective or carries too many side effects. A proper assessment of pain can greatly improve the relationship between patient and their doctor or nurse. It is also important that this is ongoing with repeat assessments to assess efficacy and the need for potential changes of management.

2.1 Obtaining a Pain History

A pain history should determine the site of pain, duration, whether constant or intermittent, what makes it worse or better, radiation, intensity and nature of the pain. It is also important to determine the mood of the patient, particularly whether depressed or not, and the meaning of the pain to the person [8]. A full pain assessment is shown in Table 22.3.

Table 22.3 Scheme for pain assessment
Full size table

3 Management of Pain

3.1 Barriers to Pain Management

A combination of clinician and patient factors contribute to poor pain recognition and management in patients. This is true for all patients, but probably happens more frequently for patients with CKD owing to the complexity of the causes of pain, the fact that many nephrologists are not trained in pain management and the difficulty of prescribing analgesia with impaired kidney function. Table 22.4 lists potential clinician and patient factors and how these could be overcome.

Table 22.4 Potential barriers to pain management
Full size table

3.2 Non-pharmacological Management

Pain perception and analgesic requirement vary between patients and with time in individual patients. Many factors can exacerbate pain including depression, loneliness, inactivity, fear and anxiety about meaning of pain. Pain management therefore includes exploring psychosocial issues with patients and eliciting potential depression and anxiety which should then be appropriately managed with psychological support and/or medications such as antidepressants [1]. Other nondrug measures for pain relief include:

  • Transcutaneous nerve stimulation (TENS): The rationale for TENS is based on the gate theory for pain. TENS should only be used for chronic pain, including neuropathic pain – there is no evidence of benefit for acute pain. It should only be administered by specialist pain clinics as how electrodes are placed makes considerable difference to efficacy.

  • Acupuncture: Although evidence of benefit is equivocal, some patients find acupuncture beneficial for management of chronic pain. Theories for its mode of action include the production of endorphins.

  • Physiotherapy and manipulation: Many people will try these methods, particularly for back pain, despite lack of evidence of benefit. Physiotherapy for patients with reduced mobility can also improve general well-being and mood, both of which may alleviate perception of pain.

3.3 Drug Management

The World Health Organization (WHO) analgesic ladder uses a stepwise approach to prescribing analgesics that selects initial analgesia according to the severity of the pain, starting at the lowest appropriate level and titrating as required to alleviate pain. An example of such an approach adapted for patients with advanced CKD is shown in Fig. 22.1 [9]. This approach has been found to be useful and efficacious for cancer pain as is now advocated for use in patients with non-malignant chronic pain, including patients with advanced CKD and those on dialysis [10, 11]. Table 22.5 outlines the five key principles to keep in mind when prescribing analgesics. Sustained-release preparations are generally not recommended in advanced CKD patients.

Fig. 22.1
figure 1

Adapted World Health Organization 3-step analgesic ladder for patients with advanced chronic kidney disease

Full size image
Table 22.5 Principles of pain management
Full size table

Most analgesics, including opioids and their active metabolites, are cleared renally. The selection of analgesics for patients with advanced CKD is therefore challenging and must take into account the altered pharmacokinetics and pharmacodynamics, especially when eGFR is <30 ml/min. Table 22.6 outlines recommended analgesics in CKD. Even for recommended analgesics, adverse effects are common; so ongoing monitoring is important [12–15].

Table 22.6 Analgesic use in advanced chronic kidney disease based on the WHO analgesic ladder
Full size table

Acetaminophen is considered the non-narcotic analgesic of choice for mild to moderate pain in CKD patients. All of the opioids can cause significant toxicity, but some are less problematic than others (see Table 22.6). They should all be used cautiously, with both dose reduction, increase in the dosing interval and regular monitoring. Patients requiring step 3 analgesics can be managed effectively with short-acting hydromorphone that can be switched to transdermal fentanyl if the daily hydromorphone dose exceeds 8 mg.

3.4 Neuropathic (Nerve) Pain

Neuropathic (nerve) pain is unlikely to respond to opioids alone. Adjuvants such as anticonvulsants and antidepressants have proven successful in this regard, though studies specific to patients with advanced CKD are lacking. Opioids may be required in addition to adjuvant therapy. Methadone may be more useful than other step 3 opioids for treating neuropathic pain. There are insufficient data or clinical experience with selective serotonin reuptake inhibitors (SSRI) and selective serotonin-norepinephrine reuptake inhibitors (SSNRI) for neuropathic pain in CKD to make a recommendation.

3.5 Other

Opioids can be abused so safe prescribing requires consideration of the risks associated with drug abuse and addiction. These issues need to be separated from physiological physical dependence, which is defined as the occurrence of withdrawal symptoms if the dose is abruptly reduced or after administration of an opiate antagonist. Experience suggests that less than 10 % of patients have the biological characteristics that put them at risk of becoming addicted. Risk is highest in patients who have a personal or family history of alcohol or drug abuse. Such patients will benefit from careful monitoring by a specialist pain team.

4 Conclusion

Pain is common in patients with chronic kidney disease and can be caused by the kidney disease itself, complications related to kidney disease and comorbidities. It is therefore important that all patients should be asked about the existence and nature of any pain, that the cause of the pain is identified and that patients are given adequate and appropriate pain control. Management of pain also includes addressing psychosocial issues as pain can adversely affect quality of life, and this in turn can impact negatively on the perception of pain severity by the patient. Renal clinicians should be aware of the complex manner in which analgesic dosing is affected by kidney function and therefore become familiar with a few analgesics for each stage of the WHO pain-control ladder. Referral to palliative care or specialist pain services should be considered for management of complex pain or when drug abuse or addiction is suspected.

Before You Finish: Practice Pearls for the Clinician

  • Regularly ask all patients with kidney disease about the existence of pain.

  • Take a full pain history to determine nature, cause and severity of pain and its psychosocial impact.

  • Ask patients about existing analgesia to determine whether this is sufficient and/or appropriate for level of kidney function.

  • Become familiar with one or two drugs in each analgesic class regarding dosage related to kidney function and likely side effects.

  • Collaborate with your local specialist pain service and refer patients.