Which has more correlation with COPD? Duration of smoking or number of sticks per day?

Dear Ask The Doctor: Dear doctor, i am a 28 yr old mother of two. recently i have been to see my doc abouta persistent cough and chest pain,(more in my spine and rib, than muscular) i also have scoliosis. With treatment i initially coughed up small Slightly yellow,greyish-black speckled phlegm,after continuing this treatment, i have no coloured phelgm IN the beginning, my doctor has listened to my breathing via stethascope to find nil result, as i persisted she sent me for an x-ray of my chest. when the x-rays were examined my doc proceeded to tell me there was nothing unusual, so she rang the radiologist who stated there were extremely slight signs of COPD. these signs specifically needed to be pointed out to her, the statement from the radiologists was "If its there,this is were it will show up". since then i have been supplied puffers ASMOL, SERETIDE, SPIRIVA and a corse of antibiotics KALIXOCIN. there were no other tests performed. I have no personal history of any lung conditions, although my sister suffered from asthma as a child. I have smoke both ciggarettes and cannabis since 16 and 18 respetively, since this diagnosis i have ceased both. I also for many years played soccer and cycled. I this a sufficient test for this diagnosis, i am afraid, uncertain and not very well informed. Should i continue to investigate this with more testing? Seek a second opinion? Thanks for you time Hayley Strong QLD, Australia

Dear Hayley: Seeking a second opinion is an option. You can also request your doctor for a pulmonary function test since this is more accurate. COPD does not get cured; however, smoking cessation can greatly deter decline in pulmonary function. It is not the number of years you have been smoking that matters; it is the number of cigarettes per day (computed as pack years) that correlates with COPD. For example, a person who smokes 5 sticks a day for 10 years will have the same risks of having COPD as someone who smokes 25 sticks per day for 1 year. For now, I think a pulmonary function test would be reasonable. After this, it will be his/her discretion if you should continue your medications