Risk of fragility fractures in patients with indolent systemic mastocytosis (MastFx score)
The MastFx score calculates the risk of new fragility fractures after diagnosis of indolent systemic mastocytosis (ISM). THe model was developed to identify ISM patients who will probably benefit from an early start of therapeutic intervention with drugs.
Research authors: van der Veer E, Arends S, van der Hoek S, Versluijs JB, de Monchy JG, Oude Elberink JN, and van Doormaal JJ.
General details Custom formula Study characteristics Files & References Validations
★★★
Model author
Model ID
647
Version
1.28
Revision date
2017-12-01
Medical specialty
MeSH terms
  • Mastocytosis
  • Bone Fractures
  • Clinical Prediction Rule
  • Model Type
    Linear model (Calculation)
    Status
    public
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    Formula
    No Formula defined yet
    Condition Formula

    Additional information

    Background:
    Fragility fractures (FFxs) and osteoporosis occur frequently in patients with indolentsystemic mastocytosis (ISM), even before 50 years of age. This prediction model aims to identify individual patients with ISM at risk of new FFxs.

    Methods:
    Data on lifetime fractures and trauma circumstances were collected from vertebral morphometry, patients' records, and questionnaires. Clinical, lifestyle, and bone characteristics were measured. Patients receiving treatment for osteoporosis before ISM diagnosis or with missing bone data were excluded from FFx risk assessment.

    Results:
    In total, 389 lifetime fractures occurred in 127 of the 221 patients with ISM (age, 19-77 years), including 90 patients with 264 FFxs. Median follow-up after diagnosis was 5.4 years (range, 0.4-15.3 years), with 5- and 10-year FFx risks of 23% ± 3% and 31% ± 4%, respectively. The MastFx score showed good accuracy (area under the curve, 0.80) to determine the risk of new FFxs. 

    Conclusion:
    The MastFx score distinguishes patients with ISM at high, intermediate, and low risk of newFFxs. The included characteristics sex, serum type I collagen C-telopeptide, hip bone mineral density, urticaria pigmentosa, and alcohol intake are easy to collect in clinical practice. The high occurrence of FFxs in patients with ISM underlines the importance of optimizing bone quality and early start of therapeutic prevention in patients at risk.

    Source: 
    van der Veer E, Arends S, van der Hoek S, Versluijs JB, de Monchy JG, Oude Elberink JN, van Doormaal JJ. Predictors of new fragility fractures after diagnosis of indolent systemic mastocytosis. J Allergy Clin Immunol. 2014;134(6):1413-21.

    Study Population

    Total population size: 181
    Males: {{ model.numberOfMales }}
    Females: {{ model.numberOfFemales }}

    Continuous characteristics

    Name Mean SD Unit
    Age 46 13 years
    Length 174 10 cm
    Weight 79 15 kg
    Body mass index 26.3 4.4 kg/m2
    Hip bone mineral density 0.93 0.13 g/cm2
    Hip bone mineral density -0.35 0.99 T-score
    Name LL Q1 Median Q3 UL Unit
    Disease duration 0.1 7.5 58 years
    Tryptase 4.1 27 296 ug/L

    Categorical characteristics

    Name Subset / Group Nr. of patients
    Smoking Yes 82
    No 99
    Urticaria pigmentosa Present 138
    Absent 43
    Anaphylactic shock Yes 77
    No 104
    Osteosclerosis Present 10
    Absent 171
    Presence of comorbidity Present 48
    Absent 133
    Patients using antimediator drugs Yes 63
    No 118
    H1- and/or H2-antihistamines Yes 55
    No 126
    Cromoglicic acid Yes 11
    No 170
    Oral corticosteroids Yes 4
    No 177
    Inhaled corticosteroids Yes 7
    No 174
    No public validations available

    Total MastFx-score:
    ... points

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    Result

    Total MastFx-score: points

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    Outcome stratification

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    Conditional information

    Result interpretation

    How this model should be used: 
    The MastFx score identifiies patients with indolent systemic mastocytosis (ISM) at high fracture risk, who will probably benefit from an early start of therapeutic intervention with drugs, such as bisphosphonates or parathyroid hormone.

    Model performance
    The accuracy of the MastFx score to predict which patients will have fragile fractures was good, with an AUC (c-index) of 0.80 (95% CI, 0.73-0.88). No calibration assessment was performed. 

    Alternative risk predicition tools: 
    QFracture, an alternative risk scoring tool validated for FFxs in the general population, was not useful in the prediction of fracture risk in patients with ISM with AUC values of 0.60 (95% CI, 0.50-0.71) for major osteoporotic fractures and 0.66 (95% CI, 0.56-0.75) for hip fractures.

    Final words of advice: 
    Efforts should be made by caretakers to optimize bone quality with adequate vitamin D and calcium intake and lifestyle changes in all patients with ISM. Alcohol cessation in these patients is highly recommended because drinking is a modifiable risk factor for FFxs in patients with ISM.

    Source:
    van der Veer E, Arends S, van der Hoek S, Versluijs JB, de Monchy JG, Oude Elberink JN, van Doormaal JJ. Predictors of new fragility fractures after diagnosis of indolent systemic mastocytosis. J Allergy Clin Immunol. 2014;134(6):1413-21.

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    Calculations alone should never dictate patient care, and are no substitute for professional judgement. See our full disclaimer.

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