N.H. Rev. Stat. Ann. § 507-C:10

This chapter applies to all causes of action for medical injury accruing after September 3, 1977, and as to such causes of action, shall supersede any inconsistent provision of law. In addition, this chapter applies to causes of action accruing prior to September 3, 1977, upon which no action has been instituted as of September 3, 1977, except that the time for bringing such actions as specified in RSA 507-C:4 shall be computed from September 3, 1977.