The phrase "a previous appointment" is correct and usable in written English.
It can be used when referring to an appointment that occurred before the current time or event being discussed.
Example: "I cannot attend the meeting because I have a previous appointment scheduled at that time."
Alternatives: "an earlier engagement" or "a prior commitment".
I have yet to see a real operation because the mere smell of a hospital reminds me of a previous appointment.
In fact, no woman had ever successfully run for the Senate without a previous appointment, and the horrified Maine political establishment hastened to get the message out that the Senate was no place for a woman.
We see a letter by Thackeray apologizing for having to cancel a dinner engagement — made more effective by the author's drawing of himself, dismayed at having forgotten a previous appointment.
After missing a previous appointment with him, I tell him that I'll pick up the tab and take out my wallet.
Patients with a blood pressure check immediately after a previous appointment may have been seen for other urgent indications, leading to an apparent increase in outcome risk.
Over 80% gave the highest rating to having immediate test results, not needing a previous appointment, and free testing, while less than 50% gave the maximum rating to privacy and anonymity.
Many flourish at a large state university like the one where I currently teach; my previous appointment at a liberal arts college, however, demonstrated that other young men and women blossom only in that type of atmosphere.
At Gates' recommendation, Congress confirmed his previous appointment to the rank of a brigadier general, with a special title of "Commander of the Horse", and authorized the formation of a corps of 68 lancers and 200 light infantry.
Also, the number of scheduled visits is not a direct marker for intervention intensity because a subject may have had a second visit scheduled because she missed the previous appointment.
When we speak, he suggests that in the previous appointment in his office, with an American businessman, a job offer in the States has been mooted.
Also in the shore party was Herlof Klovstad, the expedition's medical officer, whose previous appointment had been to a lunatic asylum in Bergen.
