Patient-Reported Outcome Tools Used to Manage OIC

Clinical Expert Commentaries   published on November 5, 2018
Jeffrey A. Gudin, MD
Pain Management and Palliative Care
Englewood Hospital and Medical Center
Englewood, New Jersey
Patient-Reported Outcome Tools Used to Manage OIC

Jeffrey A. Gudin, MD

The Practical Oncologist recently interviewed Jeffrey A. Gudin, MD, an internationally renowned pain management expert from Englewood Hospital and Medical Center and former clinical instructor at the Icahn School of Medicine at Mount Sinai, to learn more about current tools that are helping clinicians assess and manage opioid-induced constipation (OIC). In this interview, the second of a two-part series, Dr. Gudin discusses several formal patient-reported outcomes tools that have been validated in clinical trials. When used in conjunction with open communication, these tools may help clinicians manage OIC more effectively.

What tools are available to help clinicians identify patients with OIC that need treatment?

Several years ago, a multidisciplinary consensus group proposed defining OIC as a change from baseline bowel habits upon the initiation of opioids that is characterized by any of four symptoms: 1) reduced bowel movement (BM) frequency; 2) development or worsening of straining to pass stool; 3) a sense of incomplete rectal evacuation; and/or 4) harder stool consistency.1 In a 2015 systematic review, an expert panel suggested that several patient-reported outcomes (PROs) be used in OIC clinical trials, including BM frequency, stool consistency, straining, and quality of life.2 When compared with objective measures, PRO measures more effectively capture perceptions of constipation severity and the overall experience of patients with the condition. Straining and incomplete rectal evacuation are both included in the consensus definition of OIC because they are common and highly bothersome. Other key PROs include pain or discomfort, bloating, and fatigue.

Several PRO assessment tools have been developed and are being used more frequently to identify patients with OIC. Some of the most prominent include the Patient Assessment of Constipation-Symptoms (PAC-SYM),3 the Stool Symptom Screener (SSS),4 the Patient Assessment of Constipation-Quality of Life (PAC-QOL),5 the Bowel of Function Index (BFI),6 and the Bowel Function Diary (BF-Diary).7 The relevance of the currently available OIC assessment tools depends largely on the consensus definition used for OIC, but each of these resources can provide valuable information to enhance the management of these patients.8

How do the available PRO tools compare as assessments for OIC?

The PAC-SYM and PAC-QOL tools were developed to address the need for standardized, constipation-specific PRO instruments. The PAC-SYM is a 12-item questionnaire of patient-reported symptoms over the 2 prior weeks and uses bowel movements (BMs) and rectal and abdominal symptoms as its three subscales. The symptoms established in the PAC-SYM tool were adapted by an expert advisory panel for pivotal OIC studies of naloxegol. This research culminated in the development of the shorter SSS tool. The BFI and BF-Diary were PRO tools developed specifically for OIC. The BFI was designed for use in OIC studies evaluating the effects of oxycodone prolonged release (PR)/naloxone PR, an opioid agonist/antagonist combination indicated for the treatment of chronic pain.8

Items included in OIC assessment tools vary slightly. For example, the BF-Diary includes items for assessing all four elements of the proposed OIC definition and a module to identify use of first-line interventions (Table 1). The PAC-SYM (Table 2) and SSS include items for assessing all key components in the proposed OIC definition except for BM frequency. The PAC-QOL assesses BM frequency, one of the critical components of the proposed OIC definition. The BFI assesses the sense of incomplete rectal evacuation and also includes an evaluation of the ease of defecation and personal judgment regarding constipation. This may capture other OIC definition elements or outcomes that are important when assessing OIC severity, such as bloating and pain (Table 3). These symptoms are also addressed by the BF-Diary, the PAC-SYM, and the PAC-QOL tools.8

Table 1: BF-Diary Tool: Pros and Cons


  1. Time at which the bowel movement (BM) occurred
  2. Extent of straining
  3. Extent of emptying
  4. Pain associated with BM
  5. Shape/consistency of stool
  6. Inability to have a BM
  7. Bloating
  8. Abdominal pain
  9. Gas
  10. Lack of appetite
  11. Constipation treatment


  • Multiple domains enhance discriminatory ability
  • Includes assessment of medication use


  • Complicated
  • Time consuming
  • Requires e-diary for efficient use

Table 2: BFI: Pros and Cons


  1. Ease of defecation
  2. Feeling of incomplete bowel evacuation
  3. Personal judgment of constipation


  • Simple, clinician administered, 3-item tool that evaluates using a 100-point scale
  • Rapidly administered
  • Correlates with stool frequency; inquires about 7-day history
  • Minimum clinically relevant change is defined
  • Score >12 points indicates a significant change in constipation


  • Few domains limit discriminatory ability
  • Does not assess medication use

Table 3: PAC-SYM: Pros and Cons


  1. Stool characteristics
  2. Rectal symptoms
  3. Abdominal symptoms


  • Well studied
  • Correlates with treatment response


  • Based on interviews of patients with chronic constipation
  • Requires prolonged 14-day recall
  • Does not assess medication use

With the availability of these different assessment tools, clinicians can choose from a variety of scales that are suitable for measuring constipation. The development of these tools highlights our increasing awareness of OIC, but it is critical that clinicians recognize these scales are not equally sensitive to assess constipation in all patient types.

Are any of the PRO tools considered the “preferred” strategy when assessing patients with OIC?

Recently, the American Academy of Pain Medicine (AAPM) convened a consensus panel to determine the optimal symptom-based method for assessing OIC in clinical practice and to establish a threshold of symptom severity to prompt clinicians on when to consider prescription therapy. The BFI was selected by the consensus group as the optimal validated assessment tool because of its simplicity, ease of use, and clinical responsiveness. The practicality of an assessment tool may be related to its length and ease of use and scoring. With only three items, the BFI is the shortest PRO assessment tool available. Clinicians can quickly assess OIC severity by calculating the total BFI index score using the average score of the three items over only a 7-day period rather than a 14-day or longer period.8

Despite the benefits seen with using the BFI, the AAPM panel recognized that this instrument may be insufficient in some clinical settings. As such, the BFI may be supplemented with additional outcome measures as necessary based on clinical judgment and individual patient needs.8 In special cases, clinicians may consider using other questionnaires like the Constipation Scoring System (or the Cleveland Clinic Score) and Constipation Assessment Scales. These tools have been developed to assess OIC, but they have not been sufficiently validated in published studies.

What “take home messages” should clinicians keep in mind when deciding on the most appropriate assessment tools for OIC?

Several diagnostic and PRO tools have been validated as formal assessments for OIC, but it can be challenging to determine which tools are most appropriate depending on each patient’s unique characteristics. The BFI has been recommended by an expert panel, but other tools may be more useful for some patient populations. Some tools, including the Bristol Stool Form Scale, can be used in combination with others. While these tools are helpful, they should not replace open communication with patients, and clinicians are urged to ask about bowel function in every patient receiving an opioid. Most guidelines on long-term opioid therapy recommend all patients receive education on bowel hygiene and be started on a prophylactic bowel regimen. Stool softeners, laxatives, and dietary modifications often fail to effectively control OIC. Newer prescription agents are available to block peripheral mu opioid receptors without affecting analgesia and others promote motility and lubrication of stool to improve symptoms. With several tools available to formally assess OIC, the hope is these instruments will open communication lines so that patients can be directed to treatments that will improve their quality of life.


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Last modified: October 22, 2018