Which disease is more fatal: chronic bronchitis or chronic kidney disease (stage 4)?

Depends on severity: Neither disease is fatal if they are stable. However, stage 4 kidney disease tends to worsen to stage 5 disease which can be fatal. The worsening bronchitis depends on the cause (for example, common bacterial infection versus TB or not receiving the right antibiotics). Kidney disease is more likely than bronchitis to worsen without good compliance with medicines and diet and is more serious.

Chronic bronchitis: Well- I came up with the answer because breathing is quintessential for life. Not that kidneys are any less important but your question was what could be more fatal. If you were to ask what could be more debilitating or what could compromise quality of life more-- it has to be CKD stage 4. They are yet to invent dialyzersctgat you could carry in your purse like an inhaler.

Depend: Both diseases could be fatal depending on patient has other medical conditions or not because it involving two vital organs - lung and kidney. You will die without either one.