Not being privy to the formula used to calculate credit scores, since they are kept completely secret by the credit companies, it is impossible to tell what effect your breaking a lease has on your credit score.
The general public is not privy to that information. You do not even know if your landlord has reported this to the Credit Companies. IF the Landlord has a judgment against you that is unsatisfied, that can and will effect your credit score.
The previous information is solely for informational purposes only. If you have further questions, please contact an attorney in your area for more specific answers. Responding to your question in no way creates an attorney/client relationship, and none of the specific guarantees of privacy exist. If you have found this information helpful, kindly check the "helpful" box.