Prescribing of lipid lowering drugs in general practice in four health authorities, 1990-6. Linear phase r2, exponential phase r2, and change points were 0.94, 0.98, and November 1994 for Lambeth, Southwark, and Lewisham; 0.92, 0.97, and December 1994 for Bexley and Greenwich; 0.88, 0.97, and February 1995 for East Kent; and 0.84, 0.93, and January 1995 for East Sussex. 4S is Scandinavian simvastatin survival study1