Integrity of Literature on Expressed Emotion and Relapse in Patients with Schizophrenia Verified by a p-Curve Analysis

There is growing concern that much published research may have questionable validity due to phenomena such as publication bias and p-hacking. Within the psychiatric literature, the construct of expressed emotion (EE) is widely assumed to be a reliable predictor of relapse across a range of mental illnesses. EE is an index of the family climate, measuring how critical, hostile, and overinvolved a family member is toward a mentally ill patient. No study to date has examined the evidential value of this body of research as a whole. That is to say, although many studies have shown a link between EE and symptom relapse, the integrity of the literature from which this claim is derived has not been tested. In an effort to confirm the integrity of the literature of EE predicting psychiatric relapse in patients with schizophrenia, we conducted a p-curve analysis on all known studies examining EE (using the Camberwell Family Interview) to predict psychiatric relapse over a 9- to 12-month follow-up period. Results suggest that the body of literature on EE is unbiased and has integrity, as there was a significant right skew of p-values, a nonsignificant left skew of p-values, and a nonsignificant test of flatness. We conclude that EE is a robust and valuable predictor of symptom relapse in schizophrenia.