Subtipos respiratório e não respiratório do transtorno de pânico: Comparações clínicas e de qualidade de vida

Respiratory subtype of panic disorder: Can serum phosphate levels be a possible outcome to group cognitive-behavior therapy?

OBJECTIVE

Panic disorder (PD) respiratory subtype (RS) was described in order to cluster patients according to their symptoms. These patients are characterized by experiencing a relatively high number of noticeable respiratory symptoms during a panic attack (PA) and a higher reactivity to CO₂. In this study, we aimed to evaluate the clinical relevance of this diagnostic category, evaluating if there are different responses to cognitive-behavioral therapy in patients with panic disorder RS as compared to those with the non-respiratory subtype (NRS), using serum phosphate as a biological marker.

METHODS

Patients were assessed by a clinical interview followed by a structured diagnostic interview (M.I.N.I) and classified as RS or NRS based on symptoms. The severity of PD was evaluated throughout the PDSS, CGI, HAM-A, STAI and the BDI rating scales. All patients underwent 12 structured sessions of group-CBT for PD and had their blood collected at baseline and after treatment to assess phosphate levels.

RESULTS

One hundred and thirty-eight patients have been assessed, and 102 were included in this trial. Sixty-nine patients completed the treatment protocol, 42 were classified as RS and 27 as NRS. Both RS and NRS patients improved in all clinical scales (p < 0.001). The mean phosphate levels increased from 2.44 mg/dl ± 0.49 at baseline to 3.38 mg/dl ± 0.52 (p < 0.01) in the RS group as well as from 2.46 mg/dl ± 0.64 at baseline to 3.46 mg/dl ± 0.61 (p < 0.01) in the NSR group.

LIMITATIONS

Small sample size and the lack of assessment of other clinical and physiological parameters, such as respiratory variables.

CONCLUSION

Our findings suggest that both RS and NRS benefit from group CBT and that there was a change in phosphate levels after effective treatment in both groups. Our data support the idea that there is a reversal of the conditions that promote hypophosphatemia as chronic hyperventilation after CBT treatment, whereas it is in disagreement to the presence of two different PD subtypes based on phosphate levels once their rates did not differ at baseline and had a similar increase after effective treatment.

Clinical characteristics of the respiratory subtype in panic disorder patients

OBJECTIVE

Panic disorder has been suggested to be divided into the respiratory and non-respiratory subtypes in terms of its clinical presentations. The present study aimed to investigate whether there are any differences in treatment response and clinical characteristics between the respiratory and non-respiratory subtypes of panic disorder patients.

METHODS

Among the 48 patients those who completed the study, 25 panic disorder patients were classified as the respiratory subtype, whereas 23 panic disorder patients were classified as the non-respiratory subtype. All patients were treated with escitalopram or paroxetine for 12 weeks. We measured clinical and psychological characteristics before and after pharmacotherapy using the Panic Disorder Severity Scale (PDSS), Albany Panic and Phobic Questionnaire (APPQ), Anxiety Sensitivity Index-Revised (ASI-R), State-Trait Anxiety Inventory (STAI-T, STAI-S), Hamilton Anxiety Rating Scale (HAM-A), and Hamilton Depression Rating Scale (HAM-D).

RESULTS

The prevalence of the agoraphobia was significantly higher in the respiratory group than the non-respiratory group although there were no differences in gender and medication between the two groups. The respiratory group showed higher scores on the fear of respiratory symptoms of the ASI-R. In addition, after pharmacotherapy, the respiratory group showed more improvement in panic symptoms than the non-respiratory group.

CONCLUSION

Panic disorder patients with the respiratory subtype showed more severe clinical presentations, but a greater treatment response to SSRIs than those with non-respiratory subtype. Thus, classification of panic disorder patients as respiratory and non-respiratory subtypes may be useful to predict clinical course and treatment response to SSRIs.