ABSTRACT
BACKGROUND: Non-invasive ventilation (NIV) improves survival and quality of life in amyotrophic lateral sclerosis (ALS) patients. The timing of referral to a home ventilation service (HVS), which is in part based on respiratory function tests, has shown room for improvement. It is currently unknown which respiratory function test predicts an appropriate timing of the initiation of NIV. METHODS: We analysed, retrospectively, serial data of five respiratory function tests: forced vital capacity (FVC), peak cough flow (PCF), maximum inspiratory and expiratory pressure (MIP and MEP) and sniff nasal inspiratory pressure (SNIP) in patients with ALS. Patients who had had at least one assessment of respiratory function and one visit at the HVS, were included. Our aim was to detect the test with the highest predictive value for the need for elective NIV in the following 3 months. We analysed time curves, currently used cut-off values for referral, and respiratory function test results between 'NIV indication' and 'no-NIV indication' patients. RESULTS: One hundred ten patients with ALS were included of whom 87 received an NIV indication; 11.5% had one assessment before receiving an NIV indication, 88.5% had two or more assessments. The NIV indication was based on complaints of hypoventilation and/or proven (nocturnal) hypercapnia. The five respiratory function tests showed a descending trend during disease progression, where SNIP showed the greatest decline within the latest 3 months before NIV indication (mean = -22%). PCF at the time of referral to the HVS significantly discriminated between the groups 'NIV-indication' and 'no NIV-indication yet' patients at the first HVS visit: 259 (±92) vs. 348 (±137) L/min, p = 0.019. PCF and SNIP showed the best predictive characteristics in terms of sensitivity. CONCLUSION: SNIP showed the greatest decline prior to NIV indication and PCF significantly differentiated 'NIV-indication' from 'no NIV-indication yet' patients with ALS. Currently used cut-off values might be adjusted and other respiratory function tests such as SNIP and PCF may become part of routine care in patients with ALS in order to avoid non-timely initiation of (non-invasive) ventilation.
Subject(s)
Amyotrophic Lateral Sclerosis/diagnosis , Amyotrophic Lateral Sclerosis/therapy , Lung/physiopathology , Noninvasive Ventilation , Respiratory Function Tests/methods , Respiratory Muscles/physiopathology , Aged , Amyotrophic Lateral Sclerosis/physiopathology , Area Under Curve , Clinical Decision-Making , Cough/physiopathology , Disease Progression , Female , Humans , Male , Maximal Respiratory Pressures , Middle Aged , Muscle Strength , Patient Selection , Predictive Value of Tests , ROC Curve , Reproducibility of Results , Retrospective Studies , Time Factors , Time-to-Treatment , Vital CapacityABSTRACT
BACKGROUND: Carriers of a premutation (CGG repeat length 55-200) in the fragile X mental retardation (FMR1) gene are at risk for primary ovarian insufficiency (FXPOI). The anti-Müllerian hormone (AMH) level acts as a useful marker of ovarian follicle reserve and, thus, may serve to predict when this ovarian reserve becomes too low to sustain ovarian function. We investigated the intra-individual variation of AMH levels over time for premutation carriers compared with non-carriers. METHODS: We determined AMH levels in blood samples from 240 women ascertained through fragile X families, of which 127 were premutation carriers and 113 were non-carriers. Linear mixed models were used to assess the effect of age and premutation status on AMH levels and to determine a modeled AMH value. The stability over time of the deviation of observed AMH levels from modeled levels, referred to as standardized AMH values, was assessed through correlation coefficients of 41 longitudinal samples. RESULTS: At all ages, premutation carriers exhibited lower AMH levels. For all women, AMH was found to decrease by 10% per year. The added effect of having a premutation decreased AMH levels by 54%. The deviation of an individual's AMH level from the modeled value showed a reasonable intra-individual correlation. The Pearson correlation coefficient of two samples taken at different ages was 0.36 (P = 0.05) for non-carriers and 0.69 (P = 0.01) for carriers. CONCLUSIONS: We developed a unique standardized AMH value, taking FMR1 premutation status and the subject's age into account, which appears to be stable over time and may serve as a predictor for FXPOI after further longitudinal assessment.
