Severity, Irritability, Nature, Stage and Stability (SINSS)

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Overview[edit | edit source]

The Severity, Irritability, Nature, Stage and Stability (SINSS) model is a clinical reasoning construct to provide clinicians with a structured framework for taking subjective history, in order to determine an appropriate objective examination and treatment plan, and reduce clinical reasoning errors[1].

The SINSS model helps the physiotherapist to find out detailed information about the patients' condition, filter and group the information, prioritize their problem list and determine which tests should be used and when. This ensures information isn't omitted and the patient isn't under or over examined and/or treated[1].

Model[edit | edit source]

SINSS Model Graphic.png

Severity[edit | edit source]

Severity relates to the intensity of the symptoms, including subjective pain level. Amount, type and pattern of pain should be established. Pain can be measured in a multitude of ways, such as through the visual analogue scale (VAS). Using tools to help gauge the patient’s pain will help assist the clinician in objectively categorizing the symptoms. A patient’s perception of their pain can have a great impact on their recovery. A key determinant in the way severity is measured is the extent to which the patient’s activities of daily living (ADLs) are affected, as generally the more severe one’s pain is the more their ADLs are affected.

Considering the patient’s severity includes determining the suitable intensities used for the examination process.  Assessing the severity further lends itself to assessing the patients' prognosis and outcome, which supports the therapist in their overall treatment of the patient.   [1]

Irritability[edit | edit source]

Irritability can be assessed by establishing the level of activity required to aggravate the symptoms, how severe the symptoms are and how long it then takes for the symptoms to subside[2]. Irritability can also be judged by the ratio or aggravating factors to easing factors. The concept of tissue irritability was initially proposed by Maitland as the tissues ability to handle physical stress, however there are not widely used reliable or valid classifications for irritability[3].

The clinician should consider the patients' irritability when planning the evaluation and subsequent interventions. This understanding helps the clinician provide the most effective treatment. The clinician should also consider the extent to which they challenge the patient. This helps to prevent exacerbating the patients' symptoms unnecessarily[1].

Nature[edit | edit source]

Nature is a broad term relating to the patient's diagnosis, the type of symptoms and/or pain, personal characteristics/psychosocial factors, as well as red and yellow flags. Within this category a clinician should be able to recognize if the condition is within their scope of practice, as well as if the condition requires immediate action or special considerations [1].

Stage[edit | edit source]

Stage refers to the duration of the symptoms. Stage can be a useful to consider the inflammatory process and/or stage of healing. Every patient does not necessarily experience every stage of healing, nor is healing confined to these specified stage timeframes. The clinician may need to take into consideration a settled phase that occurs after the subacute phase and before the chronic stage is reached[4].

Stage classifications:

  • Acute: typically days-weeks (<3 weeks)              
  • Subacute: typically weeks (3-6 weeks)              
  • Chronic: typically weeks-months (>6 weeks)      
  • Acute stage of a chronic condition: recent exacerbation of symptoms of a condition that the patient has been experiencing for >6 weeks
  • Subacute stage of a chronic condition: later stage of exacerbation of symptoms of a condition that the patient has been experiencing for >6 weeks.[1]

Stability[edit | edit source]

Stability refers to how the symptoms are progressing, which the clinician can use within the wider context to evaluate the effectiveness of their assessment and treatment, and to guide progression or regression of the intervention[5]. The condition can be:

  • Improving
  • Worsening
  • Not changing
  • Fluctuating

Conclusion[edit | edit source]

There are multiple models of clinical reasoning. SINSS presents a methodical approach that can benefit the clinician and the patient, by allowing the clinician to gain a deeper understanding of the patient's experience which can result in more appropriate interventions[1]. Additionally, the SINSS model can be beneficial in education when utilized by mentors and their students to help facilitate the clinical reasoning process [1]. While utilizing the SINSS model in the orthopedic setting may reduce clinical reasoning errors during the diagnostic and prognostic process as well as the intervention[1], the SINSS model requires further research to confirm that its use improves patient outcomes.  

References[edit | edit source]

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 Petersen EJ, Thurmond SM, Jensen GM. Severity, Irritability, Nature, Stage, and Stability (SINSS): A clinical perspective. J Man Manip Ther. 2021 Oct;29(5):297-309
  2. Barakatt ET, Romano PS, Riddle DL, Beckett LA. The Reliability of Maitland's Irritability Judgments in Patients with Low Back Pain. J Man Manip Ther. 2009;17(3):135-40.
  3. Kareha SM, McClure PW, Fernandez-Fernandez A. Reliability and Concurrent Validity of Shoulder Tissue Irritability Classification. Phys Ther. 2021 Mar 3;101(3):pzab022.
  4. Baker SE, Painter EE, Morgan BC, Kaus AL, Petersen EJ, Allen CS, Deyle GD, Jensen GM. Systematic Clinical Reasoning in Physical Therapy (SCRIPT): Tool for the Purposeful Practice of Clinical Reasoning in Orthopedic Manual Physical Therapy. Phys Ther. 2017 Jan 1;97(1):61-70.
  5. Koury MJ, Scarpelli E. A manual therapy approach to evaluation and treatment of a patient with a chronic lumbar nerve root irritation. Phys Ther. 1994 Jun;74(6):548-60.