Central Sensitization Inventory PDF: Scoring & Interpretation

The Central Sensitization Inventory (CSI) is scored by adding up the responses to its 25 symptom questions, each rated on a scale from 0 (never) to 4 (always), for a total possible score of 0 to 100. A score of 40 or above has traditionally been used as the cutoff suggesting the possible presence of central sensitization, and a set of five severity bands helps clinicians and researchers place a score in context. The scoring itself is straightforward, but interpreting what a given number actually means for any individual patient gets more complicated than the tidy severity tiers suggest.

How the CSI Is Structured

The CSI has two distinct parts. Part A contains 25 items covering a range of somatic and emotional symptoms commonly associated with central sensitivity syndromes: things like difficulty sleeping, sensitivity to bright lights, difficulty concentrating, skin sensitivity to clothing, and feeling anxious or overwhelmed. Each item asks how often you experience a particular symptom, and you respond on a five-point scale from “never” to “always.”¹

Part B is not scored numerically. Instead, it asks whether you have ever been diagnosed with any of several conditions thought to involve central sensitization, including fibromyalgia, irritable bowel syndrome, chronic fatigue syndrome, tension headaches or migraines, temporomandibular disorders, restless leg syndrome, and multiple chemical sensitivities. It also asks about three related conditions: depression, anxiety or panic attacks, and neck injury.¹ Part B gives clinicians supplemental context but does not contribute to the numerical score. When people refer to “your CSI score,” they mean the Part A total.

Scoring Part A Step by Step

Each of the 25 items gets a number from 0 to 4 based on your response. “Never” is 0, “rarely” is 1, “sometimes” is 2, “often” is 3, and “always” is 4. You simply sum all 25 responses. The minimum possible score is 0 and the maximum is 100.² Higher scores reflect a greater frequency and breadth of symptoms linked to central sensitization.

There is no weighting of individual items, no reverse scoring, and no subscale calculation needed. If you have the questionnaire in PDF form, the math is pencil-and-paper simple. Some clinical or research settings use electronic versions that auto-calculate, but the underlying arithmetic is the same: add it all up.

The Five Severity Levels

After the initial validation work established 40 as the clinical cutoff, researchers later proposed a finer-grained framework of five severity tiers based on the score distributions from published patient samples:³

• Subclinical (0–29): Symptom levels similar to those seen in people without chronic pain conditions.
• Mild (30–39): Some symptoms present but below the clinical threshold historically associated with central sensitivity syndromes.
• Moderate (40–49): Above the traditional cutoff of 40. Symptoms are at a level commonly seen in patients with conditions like chronic widespread pain.
• Severe (50–59): Symptom burden consistent with more significant central sensitization involvement.
• Extreme (60–100): Very high symptom levels, most often seen in patients with established diagnoses like fibromyalgia.

These tiers were established from average scores and standard deviations across previously published groups of patients and healthy controls.⁴ In the original validation studies, fibromyalgia patients tended to score highest, followed by chronic widespread pain patients, then chronic low back pain patients, and healthy controls scored lowest.⁵ A score in the “extreme” range does not automatically confirm a diagnosis of any specific condition, but it does flag substantial symptom burden that warrants closer evaluation.

The 40-Point Cutoff and What It Gets Right and Wrong

The cutoff score of 40 is the most widely cited threshold, and it was derived from outpatient chronic pain populations.² In one classification study, the CSI correctly identified about 83% of patients who had a diagnosed central sensitivity syndrome, meaning its sensitivity is fairly good. But it only correctly identified about 55% of patients who did not have a central sensitivity syndrome, meaning its specificity is considerably weaker.⁶

In practical terms, if your score is below 40, it is a reasonable (though not perfect) signal that central sensitization symptoms are not dominant in your clinical picture. If your score is above 40, the questionnaire is telling you that something is going on, but roughly half the time in the validation data, people who scored above 40 did not actually have a diagnosed central sensitivity syndrome. The tool catches most of the people it should catch but also casts a fairly wide net that sweeps in some people whose symptoms have other explanations. Clinicians who use the CSI tend to treat it as a screening flag rather than a standalone diagnostic instrument, and that approach aligns well with its actual performance.

Is the CSI a Reliable Questionnaire?

By standard psychometric measures, the CSI performs well. The original English version showed strong internal consistency (Cronbach’s alpha of 0.879) and good test-retest reliability, meaning people who took it twice without major changes in their condition got similar scores both times.⁵ Translated versions have held up well too. The Turkish version showed an internal consistency of 0.92 and a test-retest reliability coefficient of 0.93.⁷ The Spanish version came in at 0.872 for internal consistency and 0.91 for test-retest reliability.⁸

A European Portuguese version validated with adolescents who had chronic musculoskeletal pain showed similarly strong numbers, with internal consistency at 0.91 and test-retest reliability at 0.94.⁹ Nepali, Korean, and other language versions have also undergone formal cross-cultural adaptation processes.¹⁰ One interesting wrinkle: the Spanish version’s factor analysis found a single-factor structure rather than the four factors found in the English version, suggesting that the way the symptoms cluster together may differ somewhat across languages and cultures, even though the overall reliability stays high.⁸

What CSI Scores Correlate With in the Body

The name “Central Sensitization Inventory” implies the questionnaire is measuring something that happens in the nervous system. A key question is whether the scores actually track with laboratory measures of pain processing. A large meta-analysis examining the relationship between CSI scores and quantitative sensory testing found statistically significant correlations across five different sensory testing methods. The strongest link was between CSI scores and pressure pain thresholds: about half the studies reported medium to large effect sizes for that association, based on data from 29 studies and over 3,000 participants.¹¹

That sounds reassuring, but the picture is less tidy when you look at individual study populations. In people with knee osteoarthritis, for example, the CSI showed only weak correlations with decreased pressure pain thresholds at both local and remote body sites.¹² The researchers in that study noted the CSI was more strongly tied to psychological factors than to the laboratory pain measures. This pattern has shown up repeatedly, and it is one of the most important things to understand when interpreting a CSI score.

The Psychological Side of CSI Scores

CSI scores consistently correlate more strongly with measures of depression, anxiety, and catastrophizing than they do with the lab-based tests meant to capture nervous system sensitization. In patients with knee osteoarthritis and chronic low back pain, depression scores showed correlations with the CSI around 0.65 to 0.67, anxiety around 0.48 to 0.56, and pain catastrophizing around 0.41 to 0.42.¹³ In people with chronic neck pain, the CSI was moderately correlated with fear of movement and anxiety, though the association with depression was weaker and not statistically significant in that sample.¹⁴

This creates a genuine interpretive challenge. If your CSI score is high, is that because your nervous system is amplifying pain signals, or because anxiety and depression are elevating your symptom reporting, or both? Recent research studying patients with temporomandibular disorders concluded that the CSI is more associated with psychosocial factors than with the more robust laboratory indicators of central sensitization, which limits its usefulness as a standalone marker for central sensitization specifically.¹⁵ This does not make the CSI useless. It means a high score is capturing something real about a patient’s distress and symptom experience, but it may not cleanly isolate the neurological mechanism the name implies.

Using CSI Scores Before Surgery

One of the most practical applications of the CSI has emerged in presurgical screening, particularly for joint replacement and spine surgery. A systematic review of central sensitization as a predictor of outcomes after hip and knee arthroplasty found robust evidence that patients with signs of central sensitization before surgery are more likely to experience persistent pain, functional impairment, lower satisfaction, and diminished quality of life afterward, even when the surgery itself goes well technically.¹⁶

The pattern holds in spine surgery. A prospective study of patients undergoing lumbar decompression for spinal stenosis found that higher preoperative central sensitization scores were independently linked to less favorable short-term recovery.¹⁷ A larger multicenter study looking at lumbar spinal stenosis patients over 12 months showed that preoperative CSI scores were significantly associated with postoperative low back pain, mental health, quality of life, and neurological symptoms.¹⁸

This does not mean that patients with high CSI scores should be denied surgery. It means the score can help set expectations and shape perioperative plans. Someone scoring in the severe or extreme range might benefit from additional pain management strategies, psychological support, or a more gradual rehabilitation timeline. Surgeons and pain teams who use the CSI in this way are not looking for a go/no-go cutoff; they are trying to figure out who will need more comprehensive postoperative support.

The CSI as a Treatment Outcome Measure

Beyond screening, the CSI can also track changes over time during treatment. One study used the CSI as an outcome measure in a functional restoration program for patients with chronic spinal pain, assessing whether scores dropped as patients progressed through multidisciplinary rehabilitation.¹⁹ The logic is straightforward: if treatment is addressing the broad symptom burden captured by Part A, the score should decline. Because the CSI covers such a wide range of symptoms, including sleep disruption, cognitive difficulties, and emotional distress alongside pain, it can pick up improvements that a pain-only measure might miss.

For clinicians tracking an individual patient, the smallest detectable change matters. In the adolescent Portuguese validation, the standard error of measurement was about 4 points and the smallest detectable change was roughly 11.5 points, meaning a shift of 12 or more points likely reflects a real change rather than normal score fluctuation.⁹ Clinicians using the CSI to monitor progress should look for changes of roughly that magnitude rather than getting excited about a drop of two or three points.

The Short-Form CSI-9

Filling out 25 questions is not burdensome, but in settings where time is tight or the CSI is being administered alongside several other questionnaires, a shorter version is appealing. Researchers developed a nine-item version (CSI-9) that correlated very strongly with the full 25-item version in people with musculoskeletal pain, with a correlation coefficient of 0.91.²⁰ Both versions showed similar correlations with pain intensity, pain interference, and quality of life.

Testing the CSI-9 in individuals with inflammatory bowel disease confirmed that the short form could adequately discriminate between those with and without pain, using a cutoff of 17 for the nine-item version compared with the familiar 40 for the full CSI-25.²¹ If you encounter a CSI-9 score, the scale maxes out at 36 rather than 100, and you cannot directly compare a CSI-9 number to the severity tiers established for the full version. The cutoff and interpretation framework is specific to each form length.

Using the CSI With Younger Patients

Most of the CSI validation work involves adults, but central sensitization is also relevant in adolescents with chronic pain. The European Portuguese version was validated specifically in adolescents with musculoskeletal chronic pain, where it showed strong psychometric properties. The correlations with psychological measures in this younger group followed the same basic pattern seen in adults: moderate to good correlations with depression, anxiety, and stress, and somewhat weaker but still meaningful links to fear of movement, sleep problems, and catastrophizing.⁹ The fact that the CSI’s association with psychological distress is strong even in younger populations reinforces the idea that this questionnaire captures a broad symptom experience, not a narrow neurological biomarker.

Distinguishing Central Sensitization From Related Conditions

In clinical settings, one of the trickiest aspects of interpreting a CSI score is separating central sensitization from comorbid depression, generalized anxiety, or other psychiatric conditions that produce overlapping symptoms. Sleep disturbance, concentration difficulties, fatigue, and feeling overwhelmed all appear on the CSI and also feature prominently in major depressive disorder and anxiety disorders. A person with untreated depression and no chronic pain condition could plausibly score in the moderate or even severe range on the CSI simply because their depressive symptoms map onto many of the 25 items.

Research in fibromyalgia populations has shown that CSI scores can discriminate among groups. One study found progressively higher CSI scores in fibromyalgia patients compared to rheumatoid arthritis patients and healthy controls, which is consistent with the idea that the inventory captures something beyond general illness burden.²² But this ability to distinguish groups at a statistical level does not solve the problem for individual patients. If your CSI score is 52, a clinician still needs to consider whether central sensitization, psychological distress, or some mix of both is driving that number. The Part B checklist helps by flagging relevant prior diagnoses, but the score interpretation ultimately requires clinical judgment, not just arithmetic.

For anyone who has downloaded the CSI PDF and scored it on their own, the most useful takeaway is probably this: the number tells you something real about your symptom load, and a score above 40 is worth bringing to a healthcare provider’s attention. It does not tell you exactly why your nervous system is behaving the way it is. The severity tiers give you a rough sense of where you stand relative to other chronic pain populations, but they work best as conversation starters rather than standalone diagnoses.