key: cord-1051351-zcsck7kt
authors: Tam, Wilson; Ho, Roger; Ho, Cyrus; Hao, Fengyi; Tan, Wanqiu; Ho, Roger
title: Reply to letter
date: 2020-12-24
journal: Brain Behav Immun
DOI: 10.1016/j.bbi.2020.12.019
sha: 8c08c43690cbc9eabc748e079aa6296c91d155fa
doc_id: 1051351
cord_uid: zcsck7kt

nan

We would like to thank Cruz and colleagues (Cruz Morais et al., 2020) for their interest in our paper and identifying the typos in the table (It should be 67.1% for female gender of psychiatric patients). We would also like to apologize the term "case-control" used in the title which made Cruz Morais et al. confuse. We could use a better or longer phase, such asa comparative study to compare the psychiatric symptoms between psychiatric patients (i.e. cases) and healthy subjects (i.e. controls), to avoid confusion but we chose a shorten term due to the word limit.

However, it is essential that we stated clearly in the Introduction -"This study aimed to assess and compare the immediate stress and psychological impact experienced by people with and without psychiatric illnesses during the peak of the COVID-19 epidemic with strict lockdown measures." (Hao et al., 2020 ) Therefore, we believe most could understand that it was a comparative study between the cases (i.e. psychiatric patients) and control (i.e. healthy subjects) to examine their psychiatric symptoms during the lockdown.

For case-control study, it compares subjects who have a disease or outcome of interest (i.e. cases) with subjects who do not have the disease or outcome (controls), and looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group so as to determine the relationship between the risk factor and the disease. Undoubtedly, our aim was not to examine the risk factor to develop psychiatric illness but compare the current psychiatric symptoms between the two groups of subjects in such unprecedent period. Since Cruz Morais et al. made their comments by considering it as a case-control study (which we acknowledge that the two words in the title might confuse them), their comments about the analyses are invalid. If it were a case-control study, we would use logistic regression to examine the association of the potential risk factor to the disease but it was obviously not the scenario.

Please note that we could only invite the patients through SMS during the lockdown period and the contact list was extracted from the database of the First People's Hospital of Chongqing Liang Jiang New Area, China (which was described in the first sentence in Section 2.1), hence, the response rate was expected to be low and we have addressed this as the limitations in the discussion. Similarly, we could only recruit healthy subjects through convenient sampling. We understand that a random sample from the population would reduce the selection bias but it would be difficult to get such sample during the lock down. Furthermore, we have provided very detailed explanation for the different inclusion criteria for psychiatric patients and healthy controls under Section 2.2.

We had tried our best to conduct the study and present the results promptly so that other researchers could have a better understanding to the issues. Once again, we are sorry that the terms in the title would lead confusion to Cruz Morais et al., but we think our results are useful for most researchers trying to alleviate the psychiatric symptoms.

Yours sincerely, Wilson Tam Roger Ho Cyrus Ho Fengyi Hao Wanqiu Tan

Do psychiatric patients experience more psychiatric symptoms during COVID-19 pandemic and lockdown? a case-control study with service and research implications for immunopsychiatry